RFID Door Access
Located on the door on 22nd is an RFID Reader ( http://www.parallax.com/tabid/768/productid/517/default.aspx ). If you have an EM41000 family RFID Tag ( ex. http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/txtSearch/28161/List/1/ProductID/503/Default.aspx ) and the tag is added to the list of authorized tags you can open the door using it.
The RFID reader is attached to the Door Raspberry Pi Via USB. The code that listens for input is here: https://gitorious.org/sudodoor/sudodoor/blobs/master/daemon_rfid.py
In addition to a system for reading and validating codes there is a node.js service for adding codes running on the RasPi. You can see the code for it here: https://gitorious.org/sudoor-addcode