I had a similar question a while ago and I broke down and bought the mighty mouse. Basically, I'm on a laptop and I wanted a mouse that I didn't have to plug and unplug from my MBP. On top of this, the MBP has a measily two usb ports and I didn't want my mouse taking up one of them.
Basically I wanted a bluetooth mouse to reduce clutter and one+ month after purchase I am quite happy actually. I switch between using the multi-touch track pad and the mouse.
One of my original problems with the MM was that it didn't look ergonomic, but by switching between the two I've felt no discomfort at all. When I used the trackpad alone for 2 months or so I was feeling discomfort which is the main reason I was prompted to buy an external mouse.
The MM is a little sucky for gaming in windows but I've been using it and it works. I am not at all a serious gamer though, obviously.
Anyways, who knows when Apple will update the might mouse. I would say not anytime soon since they just released the new iMacs with the same mouse and a slightly modified keyboard.