I was chatting with rbwhitaker yesterday on the IRC and he was considering longer-run official collab projects. Basically we'd do exactly what we do currently with the collabs, meeting up on a given day to invest 6-8 hours of work to a project, but rather than stop there we continue to work on that project indefinitely until interest in the project dies down. In which the project would go from the "official" status to the "unofficial" or even "inactive" status based on how much activity it still has. The official project would still be the primary project, but others wouldn't be restricted to working on previously less active or even abandoned collab projects of old. This would allow the collaborations to have more people working on the same project on their own time, and yield higher-quality games as a result of the added time-investment.
As far as working on the project goes, we were thinking more along the lines of a minimum weekly time investment to the project per person on the team. If the person fell below that minimum, well I don't think we talked about what would happen then, but I'd assume they'd have to get their time back up above the minimum to be considered on the team still for that given project. That way anyone on the team would be able to work on the project during hours that suit them as they wouldn't have to be on at the same time as every other team member, but still have some feeling of commitment.
None of this is set in stone yet, as even the idea of longer run collabs is just being played with at the moment. I'm mainly posting this thread to see what everyone else feels about an official collab project system where you can join the team by investing a certain minimum hours a week to the project, but get to decide your schedule that best fits you. Then when/if the official project loses interest and traction with the team, they can move on to another project and still be able to work on the more inactive project or even new people to pick it back up.