Hi,
I have recently bought a Mac Min and an Apple Bluetooth wireless keyboard/mouse combo to use as part of a home theatre setup and I'd like to add my experiences to Barry's above.
I sit exactly 3.5 meters (10ft) from the TV (according to my Receiver's auto-calibration) with no obstructions between myself and Mac Mini.
While the keyboard works just fine, the mouse is total rubbish. I have to be no more than 1 meter away for it to be smooth. After that, it is erratic and quite frankly, painful to use.
I have ordered the Logitech S530 as apparently the range on that is much better because it DOESN'T use Bluetooth. I will be sending back the Apple keyboard/mouse once this arrives.
This is not the first ive had this sort of problem with Bluetooth device range. IMO is not a good technology for this sort of application - I hope Apple move away from it in their next generation or at least do something about the limited range of the mouse.