I've been checking out Upverter, which is a YCombinator startup that's aiming to the the "GitHub for electronics" and open source hardware. So far it looks like they're very much on the right track, with excellent social and workflow tools built into a Web-based schematic editor.
They don't do PCB design yet and the parts library is still relatively small, but it's worth checking out. It would be very cool if they can find a way to be compatible with the new Eagle V6 XML files. That way you could use Upverter as a version control repository/collaboration environment, while still using Eagle's best-of-class libraries and PCB design tools.