Software :: Rsync-like Program To Sync Files Between Computers?

I'm looking for a way to sync directories between two computers, in a "two-way" fashion. Basically, I have a laptop and I have a desktop, and I want to keep a particular directory synced between the two machines. The easiest thing would be to have some kind of networked filesystem, but obviously this won't work because the laptop may or may not be connected to the internet at any moment. At any time I might be editing files on the desktop or on the laptop, and when the laptop is connected to the internet, I'd like all files on both machines to be synced to their most recent versions.

I thought I could do this with rsync but now that I've looked into a bit more it seems like it works only for "one-way" syncing. In other words files are synced from a server to a client or vice versa, but not both at once. First of all, am I right about that? And second, is there a program that will do what I want to do? OK, I guess you could do it with some SVN kind of thing but that seems like overkill. I guess if there's nothing out there it shouldn't be too hard to write a script myself to do it.