I second this one. Traditional news have little problem with their reputation. In general it's known if the newspaper/magazine describes itself as leftleaning, conservative etc..
I can imagine this to be much harder in a community with a vague, biased crowd not identifiable due to the hight amount of uncoordinated accounts participating.
I'd love to hear more thoughts on this bias-problem.
Battling organized partisanship is a problem for down the road. My hope is that, by the time we deal with that, we'll have the funding and the personnel to code up a system that enables us to test out some technical solutions to this problem. There are lots of ideas...