This seems like something that would increase people’s involvement in the forums - so I think its a good thing to look at (and test, if not too hard).
I know Jeff hates to look at Facebook except as an example of what not to do - but I think it would be valuable to look at the social reinforcement mechanisms that Facebook uses - and see if you can borrow some of them that wouldn’t be too hard to implement. This seems like something similar to what Facebook uses to pull people back to their app.