Oh yes, he did!
The details: "Adventurer Bear Grylls is back for another season of Man vs. Wild, and he's starting it off in grand fashion by giving himself a "guano enema" while in the middle of the Pacific Ocean. Not that it's some cheap stunt: Grylls is, rather graphically, demonstrating how to hydrate one's self should you ever find yourself stranded on a raft without the company of Bear himself."
The step-by-step video: http://www.youtube.com/watch?v=TtIG4TuVnvg&feature=youtube_gdata
Just lay back and think of England.