Remote-Exploit.org is releasing Keykeriki, a wireless keyboard sniffer. The project is both open source hardware and software. you can download the files on their site. Right now you can’t get a pre made board, but they plan on releasing one soon. The system can be upgraded with “backpacks” or add on modules. One of these is going to be an LCD that displays the keystrokes of the keyboard you are sniffing. Another is supposed to serve as an interface to your iPhone. Right now it has the ability to decode Microsoft wireless keyboards, but the Logitech pieces should be added soon.