You have a couple weeks to snag a registration to B2B if you still want to run but didn't get registered...you just need to find somebody that isn't running that can transfer their registration to you.

If you have a registration you don't need, or want to see if you can get or buy a registration from somebody, check out my post here: http://news.runtowin.com/2010/06/10/beach-to-beacon-now-allows-transfer-of-race-registrations.html

As of right now, there's 2 registrations available.