it looks to me to be tortoise SVN (or similar) with a user-friendly, mass-market audience.
2GB account for free as part of the "basic" package isn’t I suppose too bad…
I suppose the fact that there is a iphone client available is a point of difference, not that I’d feel the need to read checked-in source code on my phone, but perhaps the latest concept art.
Hmm, I’ve been using Dropbox for awhile and while I think it’s fantastic at what it does, I certainly wouldn’t recommend it for proper source control. It’s more of a convenience for moving stuff around and for sharing content to friends via the Public folder.
If anyone would like an invite (and hence an extra 250MB space) feel free to drop me a PM.