I've been reading a lot about agile procedures lately and I totally agree that colocation is important and a prerequisite. However, a form of online Activities (in the KDE sense) could be used to bring developers interested in an Open Source project closer to that project without boarding a plane.
There could be widgets shared online that would form the project workspace visible to anyone. Beside displaying project info, widgets could offer to get directly involved with a project. Remote developers could use those widgets for their own version of a project specific Activity and add other tools like editors.
Ideally, whole Activties could be distributed through the Project Repositories of a workbench and modifications could be layered upon that.