I work HfH construction once in a while. They hire professionals to do the important bits and the large stuff; excavating, pouring the foundation, wiring, plumbing, and often the finish carpentry. If you happen to have someone relatively skilled there, they may assist the pros; I've helped with all; wiring, plumbing, finish carpentry. But you don't let someone who is enthusiastic but doesn't know what they're doing do finish carpentry, they'll probably just wind up wrecking a lot of material. And if you let them do plumbing in an area where code requires copper pipe, you'll probably wind up with a mess that will take a pro 3 times longer to fix than if he'd just done it himself to start with.
I think the latter may be the case when it comes to this project. I really, really hope this project comes together, but as a programmer I fear that if they've built this thing from the ground up without a good basic understanding of web security, the thing may have to be gutted and rewritten to get to where it needs to be.
Lots of people can write web apps. Heck, I pretty much write web apps all day long, but I write them for intranet use, they're not accessible to the internet at large. If my stuff had to be hardened against the kind of general attack Diaspora is going to have to endure, I'd have to learn a lot more than I know now.