Regarding RailsSpace, that's a very nicely built Rails 1.2 application, and I think it was updated for compatibility with Rails 2.x. There's even a terrific book that was written about the RailsSpace application (or rather, RailsSpace and the book were written together).
But, RailsSpace became Insoshi, when the authors were so inspired by the amount of interest in a social networking site built in Rails. So while RailsSpace might be an interesting learning exercise, it's dead in terms of development. All of the authors' efforts (for more than a year now, I think) have been going into Insoshi instead, so that's where you should be looking.
