Yeah, they just added more info to http://www.mosso.com/cloudservers.jsp. Most of what streety said is correct; however, for the first three tiers, the provided storage is 10/20/40GB (not 20/40/60GB) respectively.
Not that it makes much of a difference, but it looks like the price will be $0.22/GB outgoing, not $0.20/GB. I'd edit my post, but I guess it's been too long (the edit link has disappeared).
