As far as the mouse goes, it's not a huge issue. It's nice for it to be wireless, obviously, and assuming that you're going to have other Bluetooth devices, it's nice for it to be a single protocol and a single (usually integrated) receiver.

As far as this particular mouse goes, we know that the only wireless one they'll produce will be Bluetooth, so just replace "Bluetooth" with "wireless" in the above statements.

The nice thing about Bluetooth in general is that it's a general purpose wireless peripheral protocol: think wireless USB. You can have mice, keyboards, serial devices (from serial ports to PPP to GPS), audio devices, etc. Also, there's a system by which you can "attach" a Bluetooth peripheral to a single computer so that you can have multiple Bluetooth-enabled computers sitting directly next to each other along with multiple peripherals and have them all talking to the correct thing. This was not as easy with RF-based wireless devices (though far from impossible). In addition, you can use that to do fancy things, like have the computer recognize that you're nearby because of a Bluetooth device you have on your person, like a phone.

Personally, I still think that the best single use of Bluetooth is Bluetooth headsets for cell phones. You can leave your phone in your pocket/purse and still be able to use it without wires trailing out of your pocket.