Challenge Completes May 15th, 2011 at 12PM - 09 Days, 16 Hours, 49 Minutes, 47 Seconds.
As long as you finish a WU before then, you will have contributed to the challenge. The passkey is for the SMP bonus points. Its important not to give it to just anyone though, cause they could mess us up. If you drop below an 80% completion rate, you lose the bonus points.