Yeah the bluetooth goes to sleep and never wakes up on my X61. Have to boot into another OS to wake it up again. Rebooting into Snow Leopard has it working after this.

Bluetooth will keep getting found as a network adapter each time you use OS X if you don't add it as a network adapter.

In addition to what you've experienced I've been experiencing bluetooth mouse movement slowing down when I'm copying files across WIFI. Haven't tested LAN yet to see whether it slows it down mouse movement as well. I also get weird behaviour in iTunes if I sync an iPhone through the left-hand USB port. I have to keep clicking the iPhone entry in the left window pane to update the status. I imagine there's an IRQ sharing problem between two of the following: left-hand USB, Bluetooth, SATA, PCI. The left-hand USB might be the bus the Bluetooth goes through. A couple simple tests with System Profiler should tell me if I'm correct.