My beardies love them too, but you have to squish them first! (The blueberries, not the beardies!!!)
According to h**p://www.beautifuldragons.503xtreme.com/Nutrition.html Blueberries are an ok occasional feeder, but shouldn't be a main staple of your beardies Diet.
This is a pretty awesome list, and my go to for determining if it's ok to feed my beardies something. I've been using it for some time with success.
My beardies love them too. All I do is wash them and split them open. I don't give them many. Maybe three or four over a few days and then not again until they go on sale again. They have a wide variety when it comes to meal times.
I agree on the beautifuldragons food chart. I keep a copy of that chart in my car at all times because you never know when you might need to stop at the grocery store, and you never know what they will have and what you might want to try. Variety is good not only for your dragons but for us too.