I don't think dropbox really syncs (i.e. merges documents). It just stores versions, right?
Architecture astronauts tried to build generic diffs and merges, on top of rich documents. Think SVN for Word docs. Then they though about metadata, like bug-reports and other actions. Then you can host the bug report (and the project management system, and the wiki) on top of the synchronization architecture.
Dropbox, at its core, just keeps your files and 30 days of history.
What do you mean? Dropbox syncs files amongst the computers you own and that is the most used feature I think. It is a sync. (In fact before using Dropbox I was using rsync over ssh.)
Alice has a file. Bob has a copy. They both edit it, and want the edits to be synchronized (by some sort of smart merge). That's the over-engineered syncing solutions Joel is talking about. Not just rsync.
Sorry about the semantics ... I should have been clearer.
Architecture astronauts tried to build generic diffs and merges, on top of rich documents. Think SVN for Word docs. Then they though about metadata, like bug-reports and other actions. Then you can host the bug report (and the project management system, and the wiki) on top of the synchronization architecture.
Dropbox, at its core, just keeps your files and 30 days of history.