Yes. Assuming it's supported, that is, which it may or may not be--plugging it in and sticking in a disk is the quickest way to find out. You can also bring up System Profiler and it will tell you what the OS can do with that particular device. I believe iDVD will even burn to externals now, although I'm not sure about a USB one.
If it's NOT recognized, then you're going to need a third party program like Toast or DragonBurn to get it working. That can get a little pricy, sadly. There are probably some more crude freeware options, but I don't know of any off the top of my head, since I always buy Pioneer drives since I know Apple uses them so the drivers for those are built into the OS.