Posting is now enabled with a minimum karma required of 20 - that is, you must have gotten at least 20 upvotes on your comments in order to publish a post. Or an adminstrator such as myself or Robin (by default you should bother me) can temporarily bless you with posting ability - in the long run this shouldn't happen much.
The latter is a dangerous path to go down, at least for now. But if an application has something new to say about rationality and it's something that our already iconoclastic readers haven't heard before - i.e., not the standard arguments for libertarianism or whatever - then I guess so...
Though I suppose I should be ready to lower my standards somewhat from OB-level advance screening; that which ends up annoying here can just be downvoted into oblivion or not promoted.
So to some extent... let the market decide; but you are the market, and you should be very wary of people arguing "rational" arguments for their pet topics that aren't genuinely enlightening but happen to agree with one of your own. Aside from that... knock yourself out?
The further off-topic something is, the more enlightenment you should demand from it, and the readier you should be to downvote if not satisfied?
We'll just see how it goes in practice, I guess.