That is actually from March 7th, so kinda new, but not new new. ;-)
11:00 pm on May 14, 2009 (gmt 0)
Google Image results now provide option to select which color theme to show.
Yellow, white, grey etc.
Seems like an upgrade from the previously (advanced search) for Black/White vs Color selection.
12:26 am on May 15, 2009 (gmt 0)
I think it's also a natural outgrowth of the Similar Images feature in Google Labs, which detects and matches patterns of light and dark, as well as of patterns of color, within thematically related images....