Philipp over at Google Blogoscoped has the story about text snippets seen below each image found via a Google image search (as seen below image search thumbnail). This new feature was noticed and reported on yesterday and is now live to SOME Google Image Search users. After first thinking that it was live to all Google image search users, Phillip (one of the hardest working people in Googledom) has just updated his post noting that this "experiment?" is still not visible to everyone.
It looks like (no pun intended) this might be yet another Google UI test? When I ran an image search a few minutes ago the text snippets were not visible.
Postscript: Google has confirmed with SEW Blog that this is another UI experiment.
Postscript 2: I'm now seeing the results page test.