From what Ican tell, they stick to blogs and communities like Yahoo groups, Mixi or Ning type networks. At least they sometimes link to me from those places and then I go check it out. Many of them are locked though and only available to members.
I think you could definitely start something, but the problem is getting them to join in. I don't know of any Japanese people that actually 'belong' to web sites and contribute. Some comment here and there.
Publically voicing an opinion or asking a question that may make you look incompetent aren't strong points over here. Fake it until you're caught
Hard to say, but it wouldn't hurt to try ... I think you need a good, large group to center it around and hope that word spreads.