Yes, my friend Nick has been running his Profile Race cranks backwards for at least three years now, without issue. Just make sure to use some Loc-Tite (*note* if you use the red Loc-Tite, and use too much, you'll have to heat up your pedal bosses with a blowtorch to get them off - no joke, I've had to do it with the spindle bolts on my ld Powerbites) and to really torque them down with a pedal wrench. Checking them every one in a while to make sure that they aren't coming loose isn't a bad idea, either.

However, if you're doing this with pedals with a parralelogram-shaped body (ex: Odyssey Jim C, Wellgo MG-1, S&M 101), then the pedals will be backwards (in other words, the back end will taper up, and the front end will taper down, instead of vice-versa), so you'll probably want to swap the bodies of the left and right pedals, so that they're facing the proper direction.