Not seen anyone mention this yet, I saw the new themes crop up on my Google homepage the other day so I opted for the night & day one, it changes according to your local time. If you're not using the Google homepage there's another reason for you to! The bastards still haven't fixed my bookmarks though - I lost them last year when I added an URL with a funny tag in it, and they haven't come back since. Pete
Interesting. I've played with them a little bit. It's an nice add on for those who are using this thing.
You sign into your Google account (make one if you don't have), go to the Google homepage and click 'personalised home'. Once there you'll encounter a whole range of options to play with.