We have the same problem. I didn't understand it and was grossed out so
I ran a yahoo search on eating poo and found some reasons and solutions.
I found that dogs may eat poo for several reason.
1) because they still see some nutrition in the poo that was not completely digested.
2) that during house breaking a dog may become confused on where to go and covers their tracks by eliminating it by eating it.
3) that a mother pup will eat the pups poo to keep the area clean.
4) that a dog will eat other dogs poo to remove that other dogs scent.
there was somemore but I forgot.
Solutions
1) remove the poo completely each time
2) *I would not do this one but it said put hot sauce on it to make it untasteful... To me if your there anyway and are going to go threw that trouble just remove it...

3) There is something that you can put in the food so that when they go poo it will not be looked at as good.
That is all that I can remember...
We just remove the poo everytime... we also have kids that play in the yard so this solution was already being thought of before the issue came about.
We have an appointment for puppy shots on Monday so Im talking to our vet further to better understand it. We will just be picking it up though... I would talk to your vet before adding any type of substance to food or poo.