There's Robot Wars, the ancient, which was a U.S. show. That ran for I think four years, then stopped due to uh.. administrative conflicts.
"Robot Wars" the name then moved to the U.K., where it's been ever since.
There's a particular set of shows called "Robot Wars: Extreme Warriors" which is run in the U.K. but has U.S. robots competing. The last one of those was Jan 2002 (the actual filming date, not the broadcast). They were pushing to produce an RW:EW show on the east coast of the U.S. last year, but it never happened. Haven't heard much about that show since then.
The latest and greatest "thing" in the industry is the new [link|http://www.botleague.com/|Robot Fighting League], which will bring some oversight legitimacy and standardization to the member events. It's run and attended by lots of the veterans of the sport.
I'm back now, btw, and Steel Conflict in Pomona was *awesome*. Props to Steve Brown for pulling it off! I worked with Team Delta--not competing, but providing tech services to the event: flow control, arena pre-checks, filling CO2 tanks, etc. But I spent most of Saturday and a couple hours Sunday helping fix the match schedule snafu. I'm sure if you want to hear more about *that*, it'll be all over the usual forums (as in, not here).