The only UI examples that stand out when I think of google are:

- GMail -- more for the rich use of javascript that a stunning UI. Effective, simple, and performant.

- The main website -- simple, loads quickly, etc.

- Android (Froyo and beyond) -- there are elements I really wish Apple would adopt - widgets, unobtrusive notification system, etc.

Beyond those, I really haven't seen a UI/UX example from google worth being wow'd about.

Google Maps should be on that list. Can you remember the sort of maps we used to put up with on the web?

Good call on Maps. I forgot about them. I think I forgot because I mostly use the Maps app on iOs/Android rather than maps.google anymore.

A serious minus that comes to mind on their UI/UX experience is the way they handle image search now. I'm still on the fence about "instant search"

I think you meant to say Google UI. There are a lot of instances where people think Google's UI is not polished. UX is more than just the UI you see on Android tablet. Some notable UX achievements of Google:

- Search

- Google Analytics

- Gmail, gmaps, calenders, spreadsheets, etc

- Groups

UX failures: (and yet had pretty decent UI's)

- Buzz

- Wave

Sidenote - TIL about bagcheck.com, looks pretty cool.