Daily endgame puzzle? 9/7/09- Bishop and Knight delicacy

In the last few days, I have posted a number of endgame puzzles.  An idea that just came to me was to post an endgame puzzle every day, and people could include a number from one to ten for how difficult they thought it was.  This may not be a good idea, but I think it's worth a try to post a tough endgame puzzle every day, and I know there are more endgame lovers than just me out there.  So feel free to comment on the puzzle, if it was too easy, too hard, etc. well, here it is, enjoy!  White to play and mate in two.  This one is kind of simple.  Just a quick note:  After you complete the puzzle, feel free to look back to see all of the checkmates for different moves by black.  There are some interesting ones!  This is Monday, so this is a Monday puzzle for endgames.  Trust me, they will get much more difficult later in the week!

8 marks out of 10. A subtle puzzle where the all mighty powerful queen is useless and unable to prevent mate, especially wih the knight blocker on b5!!

I find it rather interesting that the Q can be so helpless against well placed minor pieces.