According to this:

http://www.americangladia...og.com/2008/season-3.html
As American Gladiators Season 2 filters its way into Europe and abroad, fans of the show are all wondering if and when Season 3 is coming. NBC has announced tentative plans to bring back the show in the summer of 2009.
I'd be stunned if it doesn't come back. It did pretty well in the ratings (right?), plus NBC's flying on fumes these days. No way they'd kill off a cash cow.