ID this bug

[Cygnus Studios]

Anyone know what this is?

http://cygnus-studios.smugmug.com/photos/596866342_BwxBf-M.jpg

http://cygnus-studios.smugmug.com/photos/596866375_WXXHB-M.jpg

[Lord Vetinari]

Guessing some type of solitary wasp.
BVrian V.

[Cygnus Studios]

I spent a few hours looking through various online resources trying to ID this guy without much luck.
Very aggressive bee. While snapping a few flowers this morning he decided that I would make a great person to sting (got me on the back of the arm). I never noticed him until he decided to sting me. Packed quite a punch for his size. Luckily all of the bees in the area were too busy going from flower to flower to bother with me.