Could we add a feature to that aggregates updates (posted questions, answers) from specified users? Not a friend list, per se, but something like a facebook-esque 'wall' for followed individuals?
This would only facilitate user interaction in the Q/A loop, which is hardly "social networking." In contrast wth comments on the top answer to this question, I argue that it would only enhance "StackOverflow's function as a question and answer forum."
We already have the ability to star a question, so why not a user? I shouldn't have to mention that, given existing SO features, implementation should be trivial. ;)