I just received a beta invitation to the Dropbox file sync, store, and share service. I signed up and installed the software and I have to say it works pretty slick.
The software is pretty easy to use. It creates a ‘My Dropbox’ folder under your documents and anything in that folder will be synchronized with their servers. There is a public folder which allows public access to files via obscure URLs, but everything else is private. They also allow you to share photo folders, which I’m still figuring out right now. The photo viewing interface looks pretty nice though.
I’m guessing it uses Subversion or some similar revision control software behind the scenes because it behaves very similarly. Binary diffs are used to sync files and it has built in revision control. You can even access deleted files, just like in Subversion. Like Subversion, it also currently has the same limitation that renaming a file is like deleting and adding a new file, losing all revision history. (You can get around this in Subversion by renaming on the server and updating your local copy).
The web interface allows access to your files away from your linked computers and allows you to access a few account settings and deactivate linked PCs, in case yours gets stolen or something.
I also saw that beta users have 10 invitations to send to other people, so check around online if you’re looking for one. I will offer mine to some friends and family first, but check back later to see if I offer them publicly. (If you are one of the aforementioned friends or family, contact me to let me know you want an invitation).