Open Source Q&A systems, hosting your own "stackoverflow" sites

I recently decided to take a look at some open source Q&A systems, probably mostly known as Stackoverflow clones. The first one I tested was OSQA (http://www.osqa.net/).  It runs on Python and Mysql (and possibly PostgreSQL, although I didn't test). Setup was pretty easy, and everything was up and running fairly easy. I had a look at localisation as well, and it seems it uses a mix of the traditional localization tools ("gettext", .po files etc) and some custom javascript files which require a somewhat different method, at least for now. All in all, pretty easy setup and easy to get going.Another alternative is Shapado (http://shapado.com/). I decided to investigate it because it's graphical design looks a bit more polished than OSQA. It runs on Ruby and uses MongoDB for storage. My Python and Ruby knowledge is roughly equal (meaning I know Perl a lot better.. ;-), but installing Shapado and all required requisites turned out to be an absolute pain in the ass. Either Ruby with modules is moving to fast, or Shapado is too picky with what versions of required modules it needs, but either way, installing Shapado and Ruby was not straightforward. I learned a bit about the Ruby "gems" system and finally managed to get everything running, including mongodb and the required Ruby interface. Unfortunately, I never managed to get Shapado to accept any questions. It did access and store stuff in the mongodb database, but both with and without the captcha module active, Shapado never accepted my questions. Worse, it did so without any error messages, not in the UI or it's own log. I posted about it on the Shapado Q&A site, but even after waiting a few days nobody offered any suggestions on what could be wrong.In the end I learned a bit about getting MongoDB and Ruby based systems up and running, even if Shapado never decided to cooperate. I do not need a Q&A system right now, but if I did and had to select one of the two, I would have to choose OSQA for obvious reasons.