Nice idea, but....
I play a fair few MMOs but I don't think a mouse with that many buttons in such a small area is a good idea, especially for those of us with huge sausage digits. I can all too easily imagine hitting the wrong buttons by mistake and sending a raid encounter up Clusterfuck Creek.
My current dekstop uses a Razr Nostromo gaming pad and a Deathadder mouse. Same number of buttons but much, much more managable.