There's an alternative to this that's been out there for a while called LayerVault. I've tried so hard to like LayerValut, but ultimately decided it was unusable. It's unreliable when it comes to file management (i.e. saving versions of your work) which is the most mission-critical thing it does.

So very excited to discover Pixelapse and to begin trying it out.

Does this use some proprietary version control system or one of the many such as Git and SVN?