See penguins here. I also saw one a few pages earlier for Fedora. I haven't been through all of them but I suspect there'll be some other distro themes too. I'm not holding my breath for a Crux igoogle theme though... lol!

EDIT: Went through them all and didn't see any more. Just the penguins and Fedora... Oh well... I'm sure more will come down the pike in due time.