Good questions. I think we'll stay on Google Code for the time being.
As far as near term roadmap, here are my rough thoughts:
There are a number of client-side things still to enable, such as collaborator cursor/highlight, collaborator tracking, the debugging extension, etc. Jaime has more details on this stuff, so I'm not going to elaborate those.
Server side:
1) Fixes for bugs and race conditions in the file system code. For example, if you try move a directory on a Windows box, you get an AccessDeniedException. I won't be able to debug this myself since I'm losing access to Windows soon.
2) FileEditSession needs to smartly merge on-disk changes into active edit sessions. You should be able to use sed or some external tool to edit a file on disk, and have the changes merge and propagate. I can give more details on this task.
3) GC inactive (ie, saved) FileEditSessions. Probably some heuristic sorting like (file size * time since last edit) would allow us to keep the top N in memory and dump the rest. N could be determined by a target memory usage too.
4) Larger scope, we need to rethink how the server accesses the file system in general. Probably, the best model is for a single thread (or at least, a single thread at a time) to be able to hit the FS. The FileTree verticle tries to do this internally, but it's currently possible for the FileTree verticle and EditSessions verticle to race.