I almost always drop the temps once in secondary. After 2 or 3 weeks, there's still plenty of yeast in suspension. I am currently cold-conditioning (in the lagerator, at about 36-38f) a smoked porter. From what I understand, the colder the temps (as long as it's above 35), the better the conditioning, but the longer it will take. It does seem to benefit, though, with an added crispness, and a sort of polished palate profile. Very nice.
However, the longer you condition in carboys, the more yeast falls. My porter's been in the lagerator since the middle of november...so I'm sure that if I were to simply prime and bottle it as is, it wouldn't carbonate. Since I like stronger beer, I tend to age mine longer than the minimum 2 weeks...which means that I run into this problem often. What I do, in that case, is add some generic rehydrated dry yeast at bottling, and all is taken care of. Or, failing that, you could rouse the solids at the bottom of the carboy, but that will definitely affect clarity.
After bottling, I sit the bottles in a warm room (I use a space heater) for a couple weeks. I test bottles every 5 days or so. Once it's sufficiently carbonated, I take it out and put it in my cellar for conditioning @ about 60f, and I drink it when I'm ready.