Someone ELSE just noticed that the DHT11 library from adafruit didn't work on their home-built Arduino if they changed it to run at 8MHz (like the lillypad). I looked at the library code and it looks like they use timing loops to measure pulse widths and compare the widths to a magic constant of 6 to determine if the pulse is a 1 or a 0. I think that value has to be adjusted downward for an 8 MHz processor because the timing loops will be running slower.