OK, boys n' girls, check out this young wipper snapper guitar manipulator and thank me later. (see below)

I suppose the source of the 2 handed playing of acoustic guitars came from the late, great Michael Hedges.  If you do not/have not heard Aerial Boundaries (both the tune and the CD/record), you do yourself a disservice.  A must, IMHO. 

The next step in that evolution, logically has gotta be Preston Reed.  He started just a bit after Hedges, but has his own thing and has taken it several dimensions further.  http://www.prestonreed.com

Like with any new and innovative techniques (any instrument), there are the clones forever and ever, but then something/somebody else pops up.   Do check him out.  Petteri Sariola from Finland.  OUCH.

http://www.myspace.com/petterisariola

P.S. I took a master's class from Preston, back in 1991.  He hated doctors....and me, in particular.  But, he was a fine teacher.

Gene