Looks like on October 30th Google made a massive expansion to the Google Art Project - which launched earlier this year - and it went under the radar for the most part. Here's Google's official blog post about it:

http://googleblog.blogspot.com/2012/10/more-art-project-onli...

To anyone else wondering: this submission only seems relevant to google.com and not the more country-specific domains (e.g. google.co.uk). Unfortunately for many people that's where they'll be redirected to when clicking the link above.

This URL might be better: http://www.google.com/ncr - it suppresses that redirect.

Seems to happen on hover too.

Nice catch, updated the title.

I guess the button is pointless now that you are taken to search results as soon as you type.

Unless you a feeling lucky about an empty search term...

It's been pointless very probably since inception, yet they've kept it around because (official PR comms to the effect of) 'user testing says it's comforting and inspires trust'.

Which is bullshit PR. They meant 'You do a search with Google and the top result is what you were looking for... you can choose to view our ranked results or just go with what we picked as number one'

The fact they're keeping their marketing-PR-goodwill-bullshit around as a frankenstein gimmick of a button instead of good UX is lame.