Their software is a hideously complicated and over-engineered attempt to twist human relationships into math. It only works on StackOverflow because: a) The tech community was desperate for an alternative to hidebound mailing lists on one hand and expertsexchange on the other b) How to put this? A whole lot of nerds really would like to be able to reduce the complexity of human relationships to math, too, and willingly participated.
But without a userbase that's dying for a solution, any solution, and especially a userbase prepared to put up with convoluted ranking-rating-have-I-got-enough-points-to-change-my-profile-picture-yet point-scoring games the software is actually a millstone. You're not going to get a liberal arts Q&A site that takes off with those restrictions. This is why StackExchange was such a dud.
By not realising this, their solution is more of the same! "Sure, you can start a site, you just need pi+4 users to seed your initial contract bounding, then that will need to be ranked to 6 by a quorum of level 3 users, and after an initial 26-day period of zzzzzzzzzz ".
You want to create a good Q&A site, you need to have a community, and it needs to be well-tended by empathic people who know how and where to prune. The software is pretty much irrelevant. Look at http://ask.metafilter.com/ for a success story: totally flat, forum-esque, but answers are obvious, there's no chatter or bullshit, and it works on the most amorphous and wide-ranging types of questions.
There is no shortcut solution to this problem. There is no way to mathematically manage human connections like this that works in this space. The route to success is careful relationship management, not yet more programming.