PyMC is a DSL in python for (non-recursive) Bayesian models and Bayesian probability computations. I have been thinking of trying to make an ad-hoc collaborative scenario projection tool with PyMC and ikiwiki. Users would edit Literate Python (e.g. PyLit or Ly) wiki pages that defined PyMC model modules, and ikiwiki triggers would maintain Monte Carlo sampling computations and update results pages. But it won't be enough for real argument mapping without decision theory (and possibly some other things).