Really, it should just be picked up. Doggie poop (and other carnivores' feces) are bad for the environment.
We pick ours up everyday and put it in one of these:
http://www.dog.com/itemdy00.asp?T1=250204+001&Cat=

This was a part of my Ecology project and we go it for free. We did a whole lesson on water quality and how pet feces effect it.