I recently bought a Rocketfish Bluetooth dongle for my computer so that I can see about hooking up the Wiimotes to it. Unfortunately it didn't work out of the box, but it was detected by lsusb. Here's how to get it working.
First, see if it is detected when you plug it in. The little light should be on, and if you go into a terminal (Applications->Accessories->Terminal) and type:
lsusbYou should see a "Primax Electronics, Ltd" and/or "Broadcom Corp." (I get 3 of these) in there. If you've gotten this far, good. Otherwise it is possible that your adapter is broken, try testing it on another computer.
Second, you need to reset the device, not sure why. In the terminal type:
sudo hciconfig hci0 resetThis should print out a list that looks like this:
sudo hcitool dev
Devices:This should make the device work.
If you go into System->Preferences->Bluetooth you should now be able to set up your Bluetooth devices. Click the "+" button, which will go through the little wizard. On the "Device search" page, wait a second while it detects the devices (theres a few little usability issues in the Bluetooth thing, supposedly the fixes are in for Karmic) and you should see your other Bluetooth device(s) pop up in the box. After that theres usually some kind of pairing system that you'll need to do, it depends on the device you're trying to connect. I tried with my cell phone and you have to enter the pairing code on your cell before it lets you connect the two.