I don't know about the watchdog issue, but I just went through the brownout business a couple of days
ago. This info is VERY difficult to track down, no matter what anyone says, and the bits and pieces are
scattered all over the darn place. See Post #16 on the following thread,
I have it as 2.7V, assuming I actually did find the correct source [jeesh], but this explains why I am able
to run my Duemilanove and UNO chips at both 5V and 3.3V.