Could a development portal like SourceForge, Trac, or DrProject be built as a Facebook application? OK, that's poorly-phrased: clearly, one could be. Would it make sense to do so? Privacy would be one big concern (esp. for non-open source projects), and I'd worry about it disappearing without warning due to a court order or an acquisition (but that's a concern for SourceForge, Google Code, and every other hosted service too). On the other hand, a Remember The Milk-style shared to-do list would be straightforward... And a bunch of stuff like account provisioning would be taken care of for you... Hm...