Uh, it's not a new concept. I had foot switches for typing back in the late 80s. I knew quite a few people in the 90s that were big on the concept too. It was a bit of a fad when the first round of ergonomic keyboards started becoming popular.
For a non-anecdotal perspective, emacs users have been doing this for quite a while http://emacswiki.org/emacs/FootSwitches. go ahead and search for foot switches as well. They all look old and dated don't they? There's a reason for that.
It's not talked about much because it's difficult to learn, non-portable and the need for foot switches is mitigated by proper technique when typing.