Is peanut butter bad for dogs?

I have had an ongoing debate about the fact that peanut butter is not bad for dogs. I swear over the course of my life I have been present on more than a handful of occasions on where dog owners(including my family) have given peanut butter to dogs.  I have also scoured the web and from the various posts I have see there is no evidence that giving dogs peanut butter is in anyway bad.  Just wanted to run a poll to see what others think of this, feel free to comment as well.

Update: I should note while I am wondering about dogs in general the other part of the question is does it make a difference if its a small breed puppy or a huge pit or something.