Yahoo has one upped Google today, with a special logo for the 20th anniversary or birthday of the Americans with Disabilities Act. The act was set up on July 26, 1990 by the 101st United States Congress. You can learn more about this law at Wikipedia.
Google has no mention of the important day on Google.com, but Yahoo does. Here is Yahoo's animated logo:
Here is a static version of the logo:
The logo links to yahoo.com/accessibility/2010/.
Forum discussion at Google Blogoscoped Forums.