We just released a very small Infrared Receiver board for the Raspberry Pi: this little board plugs right into the Raspberry Pi's GPIO connector and decodes infrared signals sent to it from just about any generic IR remote control. This IR receiver is tuned for a 38kHz carrier frequency but it will accept IR frequencies slightly above or below that at the cost of a reduced range. The IR stream is fed to the Raspberry Pi on GPIO #18, which is the default pin used by the Raspberry Pi's LIRC GPIO driver.
For more details: http://nwazet.com/nwazet-pi-ir-receiver-with-remote
Nwazet Pi IR Receiver with Remote