After some hiccups with delivery, the bluetooth keyboard and mouse I ordered had miraculously turned up at the leasing office on Sunday, when we poked our head in on the way home in the early evening.
I had a quick play at getting them working. The USB Bluetooth adapter was recognised by Debian Etch's 2.6.17 kernel without and problems, and I installed all of the BlueZ packages and had it happily looking around for devices.
I tried to get the mouse working first, as the documentation said that it didn't require a passkey. I successfully paired it using hidd --connect bdaddr whilst having it in discoverable mode. Sure enough, some extra stuff turned up in /dev/input (interestingly, whenever the mouse (or keyboard) puts itself to sleep, everything vanishes again, and when it reawakens, it scores a new numbered "input" entry in /sys/class/input, so I wonder if that's going to do anything unpleasant when the number gets sufficiently high).
I next tried to get the keyboard working, expecting more of a fight, because it required a passkey. Turns out, I could get it connected and working with exactly the same procedure. No passkey required. That bothers me slightly.
So at this point, I added what was essentially a second mouse device to my xorg.conf (which I suspect became redundant after I disconnected the USB mouse), restarted X, and hey presto, either mouse worked. I then removed the USB keyboard and mouse, restarted X again for good measure, and everything continued to work.
As I haven't touched a config file yet, restarting the bluetooth services loses the pairing and I have to repeat everything, so I need to figure out how to make this all "just work" at bootup, but it's not high on the list of things to do, as I don't reboot my MythTV box very often, and I use the keyboard and mouse even less.
In terms of functionality, the wheel on the mouse isn't working. This appears to be a bluetooth-level problem, as doing a hcidump shows no activity whilst the wheel is being used. Interestingly, it works as a button, just not as a scroll-wheel.
Similarly, on the keyboard, none of the grey extra buttons work (nor does the wheel).
Some preliminary Googling shows people having similar problems, and there are mentions of kernel patches. I need to do more research. I also need to do some bluetooth pen-testing with my laptop to figure out if the keyboard is really as secure as I'd like it to be.
Oh, and "Windows XP only" be damned, the thing works fine (enough) on Linux :-)