There is no need to 'jailbreak' it. It's built with the same idea as the Nexus phones. It isn't 'fastboot unlock' but Glass has a specific command in adb to unlock, so you can root it. Takes less than a minute, no need for exploits.
Apparently the previous person to provide your overall commentary got downvoted enough that you likely don't see my response anymore, so I will respond more directly here (making this reply sadly somewhat repetitive: I'm sorry).
First, it actually does have fastboot oem unlock, and no: there is no "specific command in adb" to unlock it; the command you are seeing people post reboots the device unto the bootloader, which can then be used with fastboot oem unlock.
However, that isn't helpful; in fact, I had to use an exploit (not one I came up with: a known one that affects all Android 4.0/4.1 devices) to accomplish this. (So, my device actually still has a locked bootloader ;P.)
In order to go from "unlocked bootloader" to "root" you need a new image to flash. The most common way to get this is to dump the kernel from the device (as you know that that works), but guess what: you can't, as that requires root.
The alternatives are either to have a stock image from the manufacturer that you can extract a working kernel from (something Google did not provide for the Glass, at least yet) or to build your own from the Linux source code.
Building your own kernel is, of course, possible, however it is quite irritating, and there is no guarantee the result will work as there might be binary blobs in loadable modules that you need, or other irritating hardware checks.
You also need a good feel for what hardware the device has for this to be an option, and Google disabled access to /proc/config, which makes the process of building a vaguely compatible kernel all the more like guess-and-check.
So no, it isn't at all clear to me that it is so obvious that you can go from nothing to "modified software" on the Google Glass. I'd like to see Tim Bray explain how he'd easily go about hacking on the thing ;P.
This is especially the case as the Glass Guide (the fancy term for the Google Glass sales person) who gave me the glass (I chose the option to go to Google HQ to pick it up in person) seriously told me that the debug mode feature (which gives you adb shell) is something that he thought they removed from the units they were distributing. (I guess I was the first person to find it during the at-Google demo and then ask what it would let me do ;P.)
Google disabled access to /proc/config, which makes the process of building a vaguely compatible kernel all the more like guess-and-check.
Is there really no .config in their GPL release? AFAIK compile-time config is a GPLv2 requirement as part of the "scripts used to control compilation" (Gpl-Violations FAQ specifically mentions Linux .config files.) I'd hope there's either a .config or a defconfig that applies to Glass as-shipped.
(NB: I don't mean to dispute your overall point by this, just wondering.)
I cannot find one for the "glass-1" (or, to be clear, for any glass). I've also tried searching around the device hierarchy of git repositories they have, and cannot find anything for glass{,-1} under various vendor names (including "google"). I really just don't think they posted anything.
Could you expand on why you need a image with a kernel? I rooted my nexus 4 by unlocking the boot loader, installing cm recovery, and flashing a zip that just contains superuser and busybox binaries. Is there a key difference with Google glass?
The critical step is "installing cm recovery": ClockwordMod is an image that you can boot, and which you chose to flash to your recovery partition (which is how most guides recommend you proceed, so you can easily access it while on the go; you don't actually need to do this: you can just boot it from RAM using "fastboot boot"). To make a working copy of ClockwordMod (or any similarly custom recovery), you will need to be able to build or dump a kernel for that device.
There are some pretty serious potential health consequences for the improper use of such a device.
In this case, I actually don't blame Google for keeping things locked down a bit until those are better understood.
The best I would hope for is for them to provide some amount of support for custom OEMs... but allowing people to do whatever they want on the device without some real barriers / safeguards would expose them to enormous liability.
There are some pretty serious potential health risks for the improper use of your laptop and mobile phone too. Each can easily start a fire. Your laptop's keyboard is likely damaging your wrists. Small text, dimly lit screens, and hours upon hours of constant use are hurting your eyes.
Maybe we should take away root access to your computer while installing software that forces you to take a break every few hours? Maybe require some APIs that lock you out of your Google account during that time period so you don't cheat with another device (like your cell phone).
"I worry that Google and certain other companies are neglecting some important lessons. Their design decisions could make it hard for many folks to use these systems. Worse, poorly configured products might even damage some people’s eyesight and set the movement back years.
My concern comes from direct experience. The very first wearable computer system I put together showed me real-time video on a helmet-mounted display. The camera was situated close to one eye, but it didn’t have quite the same viewpoint. The slight misalignment seemed unimportant at the time, but it produced some ___strange and unpleasant results. And those troubling effects persisted long after I took the gear off.___" http://spectrum.ieee.org/geek-life/profiles/steve-mann-my-au...
(FWIW, that specific set of issues was not related to having a monitor in his peripheral vision, but replacing his eye with the output of a camera that had a slightly different perspective, something that Glass does not attempt.)
That specific issue, but this one is relevant to how Glass is designed:
"Using lenses in this way forces one eye to remain focused at some set distance [the screen] while the focus of the other eye shifts according to whatever the wearer is looking at, near or far. Doing this leads to severe eyestrain, which again can be harmful, especially to children."
His solution is to not use a lens, but a pinhole:
"My pinhole aremac is the reverse of a pinhole camera: It ensures that you see a sharp image through the display, no matter how you focus your eyes. This aremac is more complicated than a barrier with a pinhole, though. It requires a laser light source and a spatial light modulator, similar to what’s found inside many digital projectors. With it, you can focus both eyes normally while using one eye to look through the mediated-vision system, thus avoiding eyestrain."
But that is the entire thing that makes Google's phones fundamentally better than most other phones[1]! They are, by design, entirely hackable. If you wish, you can get root on your phone; they explicitly make them this way. You're "allowed" to. No security exploits needed.
And, if they are true to their word--and there's no reason to think they won't be--the same will go for their computer-glasses.
[1]: EDIT: I mean that they are objectively, indisputably better in this fundamental way (of being expressly hackable by design). I am not saying Google's phones are better in all ways.
Well, when they come out in the end and are easily hackable (they provide stock images, they provide the source code for everything in a way that we can compile, etc.) then that will be great, but as long as I'm having to use exploits to easily get root on the device (which I did) I'm going to say "jailbreak" ;P.
I was mainly replying to the notion that hackable devices are a "dying category". Clearly that is something we are gradually losing, in this age of the DMCA and locked-down app stores. But Google is one of the few major smartphone/table companies bucking that trend.
Hopefully, this will continue to be the case, although they have been slow sometimes in getting it all sorted out when new hardware comes out...
Computers got to where they are because they were hackable, not because they were locked up.