Google has been known to continually improve upon the look and feel of their search site, but I just came across some changes that are a bit more substantial than a traditional Google refresh or improvement. This "redesign" includes a blue search button, eliminating the Google Search and I'm Feeling Lucky buttons and more changes on the results page.
The homepage now includes a voice search feature that will automatically use a built-in microphone or one attached to a webcam (thanks to HTML5).
They also seem to be trying a completely new color scheme in the left rail of the search results page, as well as a gray bar across the top.
There's a good chance many of these changes will never go live. A couple years ago, Facebook redesigned and tested their signup process but it didn't last long.