bbPress is the only forum, that I know of, that offers this out of the box. I thought for a while that I was stuck with that, which would have been okay if I did’nt want alot of cool features for my forums, but then I discovered a great mod for SMF that neighter vBulletin nor PHPbb seems to offer at the moment. The only solutions i could find for these platforms would carry some random numbers in the urls. And thanks to the great “package” section at the back end of SMF it only takes a few clicks to install it. The mod is called Pretty URLs and you can get it here!