Schneidereit, the rankings list cited by caitylin is based solely on "research output" (which is supposedly derived by counting how many times the name of one of that school's teachers popped up in certain databases). As the authors themselves state, this ranking is of little value to someone trying to choose for an undergraduate architecture program.
If you search the CC archives, you'll find other lists that are perhaps more relevant to your situation, such as the DI list of BArch programs. I would still caution you, however, that all rankings are suspect, but the DI rankings will at least give you a starting place. The link below will get you to an extended discussion about the most recent DI rankings:
America's Best Architecture & Design schools