It's a cool idea, but it might be really difficult to pull off.
1.) People may not have time
2.) People would have to choose, and FOLLOW a designated "Project Leader"
3.) Not everyone knows the same languages (Although, choosing something like the .NET Framework would help because people could choose freely between like 4 languages C#, VB, C++, J#, JScript)
4.) People would have to agree on a project, which might be hard.
But if people are willing it could end up being fun. I'm going to start an IRC Channel for those of you that want to join or discuss this idea. It will be #tech-forums on the EFNET network....you can go download a free copy of mIRC if you don't already have one.
http://www.mirc.com/