There's a competition coming up in Seattle, the Seattle Bot Battles 9.
Here's the link: http://www.westernalliedrobotics.com/ or http://www.buildersdb.com/eventdetail.asp?eventID=331
It will be in the center house at the Seattle Center in Seattle, Washington. It's on 4/10/2011 from 10:00 to 5:00 (safety and registration from 10:00 to 12:00). There will be antweight (1lb), beetleweight (3lb), hobbyweight (12lb), and Sportsman (30lb) classes.