Several things suggest now would be a good time to reorgaize the object directory. This would be annex.version=2. It will be slightly painful for all users, so this should be the last reorg in the forseeable future.
Remove colons from filenames, for fat support
Add hashing, since some filesystems do suck (like er, fat at least :) hashing objects directories (Also, may as well hash .git-annex/* while at it -- that's what really gets big.)
Add filesize metadata for free space checking. (Currently only present in WORM, and in an ad-hoc way.)
Perhaps use a generic format that will allow further metadata to be added later. For example, "bSHA1,s101111,kf3101c30bb23467deaec5d78c6daa71d395d1879"
(Probably everything after ",k" should be part of the key, even if it contains the "," separator character. Otherwise an escaping mechanism would be needed.)
done now!
Although free space checking is not quite there --Joey