This instructable will walk you through the process of dismantling and hacking a Schlage electronic deadbolt in order to control it with an arduino.
Step 1: Purchase the Lock and Unpack It
I got mine on sale for $99 at Lowe's.
Remove it from the box and take a look at what's there. The construction of the lock is really great. Anywhere that could even remotely see any moisture is surrounded with rubber sleeving or a rubber o-ring. The lock has 3 basic parts:
outside portion: This portion has a regular key cylinder, a knob for the deadbolt similar to what you normally see inside of a house, and a keypad for entering the code.
inside portion: This portion has a knob to operate the deadbolt, a housing for a 9v battery, and a switch to tell the electronics in the front of the lock when the lock is in use.
deadbolt mechanism: This portion is similar to any other deadbolt on the market.