SyncPad is a project idea which is very simple. A notepad which synchronizes itself across a groups of machines. You can sit down at any of them, make changes, and eventually all changes end up in a consistent shared state again.
Replication is a very complex issue to get right.
Maybe Wikit is the new incarnation of the Syncpad idea - it definitely has the right strcuture to evolve into (or incorporate) such a mechanism.
There has been some private discussion to further generalize these issues into a new experimental project (called Scrap).
Will Duquette has started on a local-only system called Notepad [1].