A.B.
My daughter was a biter around that age. How are his verbal skills? He probably bites when he is frustrated and can't find his words. So you should consistently remind him to use his words when he is angry, and that biting is for food only, not friends. There is a Yo Gabba Gabba episode and book about this that may help:
http://yogabbagabba.com/module.402.dont-bite-your-friends
http://www.amazon.com/s/ref=nb_sb_noss?url=search-alias%3...
We also got the book "Teeth Are Not for Biting" for our daughter:
http://www.amazon.com/Teeth-Biting-Board-Book-Behavior/dp...
Also, what is the day care doing to discipline him? Any response to the biting has to be immediately afterward to be effective, I would think. Your talking with him about it or giving him a time out well after the fact isn't likely to work.