The Basics:
What: A password cracking contest sponsored by KoreLogic.

Where: DEFCON 21 at the Rio in Las Vegas.

When: The contest lasted 48 hours:
11:59 PM PDT Aug 1 - 11:59 PM PDT Aug 3, 2013

Who: Teams with at least one team member attending the conference.

Why: To help push the envelope of password cracking techniques / methodologies and win a prize while you are at it.

Winning: There will be prize pools for a "Pro" class and a "Street" class of competitor. Plus, there will be small hourly prizes.