The part of what kleinbl00 says that resonates is this: I'm probably not going to be interested in following too many people, because I already have a long list of them that I "follow" elsewhere (i.e., Glenn Greenwald, Amy Goodman, etc.)
Reddit's double-edged greatness/weakness is its subject-oriented approach. And I think if hubski grows into quality, it will be because it finds a creative way to go that direction without ghettoization.
Tagging is a good start. I don't think it'll scale well on its own, though. I'll keep thinking on it and watching what happens, and if I come up with anything more intelligent to say, I'll keep you posted. ; )
Edit: Not OP, but kleinbl00