@markduet, yeah, that is a no no .... but shouldn't have blown up anything. See the other suggestions for proper hookup.
Edit: forgot about the input caps on the converter but didn't think there would have been enough current for long enough to kill the mosfet. I guess they are more sensitive than I imagined. Since the input caps don't have to do AC to DC conversion, they don't need to be that high a value (or so I thought).
Edit2: I prefer the theory that you inadvertently shorted the fan output somehow (unfortunately it happens, sometimes more than once <sigh>) but what do I know,
Replacing my fets was fairly painless although not real pretty. I opted to cut the leads so I was able to deal with one pad at a time.