Feature: Add support for WPA/WPA2 packet decryption.
Currently, FireSheep doesn't work if you are on a WPA/WPA2 network. If you deauthenticate everyone (other than yourself) you can capture all the handshake information you need to decrypt other people's packets.
Then FireSheep can do its current work.
Then FireSheep works on WPA/WPA2
this would be a great feature
for your interest. airtun-ng is able to decrypt wep packets on the fly, replaying them back to a virtual device. You can then setup firesheep to read from that interface, and you're done. You need one of these two tricks though: since firesheep checks that the interface has an ip address (why!?), you either patch firesheep to ignore the lack of ip address, or give the interface a random one.
wpa decryption is currently broken in the aircrack-ng. So you have to wait for a fix, or search for a user-made patch (I saw a couple of them around, but I'm not sure if they work).