It looks like google will end up with the largest and most complete spam collection in the universe if they do keep all emails , what a feat.
I am under the impression that google will put ads at the bottom of your emails akin or worse than msn and yahoo (don't quote me, but that is what i understood from something i read the other day). I refuse to send others garbage, as it is classless and crass. So i will probably not be using there service and well, a proper domain for email is more respectable and presentable. (john83452344@google just sucks)
The one redeeming feature that i would make use of is the 1 gig. If you can search your messages with great speed it would be useful for multiple high volume mail lists , eg a bugtraq, vulnwatch, full disclosure..... a quick and easy personal database of many security lists?