Google Italia says (in its official italian blog) that iGoogle's themes hide some easter eggs. for example, at 3.14 am, every night, and only for one minute, you can see this:

blogger.it.googlepages.com/Tea ...

Tony found some a while ago:
ruscoe.net/blog/2007/03/google ...

BTW, here's their post:
googleitalia.blogspot.com/2007 ...