I have a vague recollection that they had a user driven project to translate the interface, but I can't find the link.
(I use Gmail in German)
The search interface has been available in Irish for aeons, and I think blogger is also translated.
There was a discussion here a year ago or so
http://www.daltai.com/cgi-sys/cgiwrap/daltai/discus/show.pl?tpc=21&post=72215#PO ST72215