Today I received my Microsoft Bluetooth 5000 Notebook Mouse from Amazon.com. The mouse is very light compared to the Apple Wireless Bluetooth Mighty Mouse due to it using smaller AAA batteries.  The mouse is not as thin as other mice.  I find it’s not as ergonomic as the Apple Style Mighty Mouse.  One good function is the mouse has a low battery indicator to remind you to change the batteries.
You can find more about the mouse here.