22 May 1980 is the date of the first released of Pac-Man arcade game in Japan (more info here). If you visit www.google.com today 22 May 2010 (Pac-Man 30th Anniversary), you will found out that the Google homepage theme for today is Pac-Man.
The nice thing about this Pac-Man theme is you can “play” the theme. For this Pac-Man theme, the “I’m Feeling Lucky” button is being changed to “Insert Coin”, and if you click this button, you can play the Google Pac-Man, and you are “playing” the theme. Nice work Google!
Below are some video of me playing the Google Pac-Man, nothing special, but you can have a look in case you miss the game.