
While updating my Debian notebook's Linux kernel today, I found out that starting with Kernel 2.6.8 the Bluetooth subsystem comes with HID support available by default. After loading the hidp module, I was able to use the hidd utility which is part of the bluez-utils package to connect directly to my Bluetooth Mouse and use it under X.
Works really well, and also handles the reconnects the mouse sends to my notebook after disconnecting due to inactivity.
(note, for older kernels there's an alternative driver which I've used in the past available here)