Mark Nottingham thinks that using WebDAV and a client cache in front of the WebDAV server could solve some of the offline/synchronization problems posed by mobile computers. He notes that the problems that arise in this approach have to do with versioning and items changing underneath. I think that if you combine the client cache with something like Subversion, which is already based on WebDAV and DeltaV, you might have an interesting solution. The problem of resources changing behind your back when you also have changes is what Subversion is all about. So "all we have to do" is build an offline aware client side cache for Subversion...