I had a working setup for months. The other day, my rpi decided to stop connecting to my wireless. The wipi LED wasn't coming on at all. Troubleshooting it seemed to indicate USB power issues since a wireless keyboard dongle LED wouldn't light up either. I eventually got a different USB keyboard working, but the wipi continues to do nothing. Editing
/etc/network/interfaces got it to behave differently but not better. Sometimes when booting, it shows the colour screen, then reboots and repeats. Pulling the wipi out, it can then finish booting.
ifconfig is showing absolutely nothing for me.
sudo ifup wlan0 has it enter the boot cycle again until I remove the wipi dongle.
For being marketed as a raspberry pi accessory by element14 themselves, this dongle has been nothing but trouble.