I have this usb adapter working under Ubuntu 10.4 but only after blacklisting the rt2x00 modules
If you are new to Linux and prefer not to mess under the hood then this device isn't for you.
If you willing to give it a go simply do this,
1. Unplug your USB WiFi adapter and restart your computer.
2. In terminal: sudo gedit /etc/modprobe.d/blacklist.conf
add these lines to the end of the file:
Save the file
3. Insert your USB wifi device.
I only give it 3 stars because of the need for the blacklisting which shouldn't be necessary since its listed by the manufacturer as Linux friendly.