Spelt Breads

I was pleased to read here that spelt breads are quite tasty (for some reason I thought they'd taste like cardboard - or worse). How does working with spelt compare with working with wheat? For that matter, is spelt actually a different form of wheat, or botanically a different grain? Is it usually tolerated by individuals who can't have wheat? Is there a treatise on baking with spelt somewhere? Have I asked enough questions yet? :D Do I really have to quit now and get some work done? Uh, yes. :(