For everyone out there who thinks old Pappy Bush was "deep Throat" there is now a way you can research it for yourself: Woodward and Bernstein's notes and writings on Watergate are available online at the following link:
http://www.hrc.utexas.edu/exhibitions/online/woodstein/tfd/index2.html
The University of Texas at Austin purchased them for a cool 5 Million.
Hwoever in my personal opinion, if believing what Ben Bradley says the "deep Throat" is near death and the Bradley has already written his obituary, I am going to take a wild gues and say Deep Throat was Cheif Justice, William Rehnquist. I say this because: A) Rehnquist has a form a cancer that makes his demise imminent and B) He was Assistant Attorney General under the Nixon Administration, and probably knew full well what his boss, John Mitchell, was up to, as well as the shenanigans of the rest of the Whitehouse.
It makes perfect sense.