Some of the authors of [AFS] realised that [AFS] worked quite well for a while if you unplugged the network (since it caches everything on the local disk) but when writes occured issues arose. So as a research project they decided to work on Coda. Coda allowed fully disconnected operation -- you could take a laptop with wireless and wander in and out of range and it would correctly handle syncing all your files up, notifying you if there were conflicts. Coda was quite a success, then the people working on Coda decided that they could do better... 

  

 ... So they sat down and started working on Intermezzo, Intermezzo is based on the same principles as Coda, along with the idea that Intermezzo should be as fast as using a local filesystem, and should do everything over well established protocols (such as [HTTP]). From what I have seen Intermezzo isn't anywhere near production quality yet, and Coda isn't used much and has been abandoned by it's developers. [AFS] however sounds like a great li'l network filesystem.