you need a minimum temperature of 225 in order to get that rich, savory taste and color that come from browning. there's something magical that happens to meat at those temperatures and i am sure there is some science to explain it, but i prefer to think of it is "getting good."
in my smoking experience, i've found my best cooking temperatures to be in the 240-250 range. even if it gets up to 275 for a few minutes (i use a charcoal smoker) i don't worry too much about it.
bottom line: "low and slow" can be taken too far.
one caveat: if cold smoking some meats, scuh as sausage, smoked fish etc., you want temperatures even lower than 215. 180 degrees, if i rememebr correctly, is more appropriate for these types of specialties. for cheese, you want to go lower still - try to keep your temps below 90 degrees. other than that, shoot for something between 225 and 250 and you will enjoy your meat much more.
 as dude said, for poultry you want to go even higher - the reason for this is that poultry is already tender and does not require "low-n-slow...."