Apparently it was the FBI guy. (W. Mark Felt, the #2 guy at the FBI then. Now 91.) No confirmation yet, though.

Interesting. Woodward and Berstein were heros of mine in high school, and I was the mystery drove me crazy for years.

Ahhhhh, but then I read a few more Woodward books and learned the dangers of taking yourself of not understanding your limits. And slowly, ever so slowly developed a little patience. Been waiting 30 years for this secret, though.

Can't wait to hear the rest of the story. Like did Deep Throat really move the flower pot around on his apartment balcony as a signal, or did they do something similar, but fabricate that detail to deflect suspicion from him? It will be a very interesting discussion if details were changed. Interesting and annoying. Journos can be such nitwits.

Update:

Slate has posted an archive of their bouts of speculation on the identity. A lot of speculation. Very interesting to catch a glimpse of how it played out. And at least one of the pieces cites the "definitive" Deep Throat piece as an Atlantic story way back in 1992 where James Mann correctly deduced it had to be an FBI guy.

Slate's Timothy Noah repeatedly cited Felt as the most probable source. And guess who else got it right? Richard Nixon. That according to this 1999 Slate piece highlighting Mann's theory.

But perhaps the most interesting aspect of the 30-year secret is that Berstein's kid blurted it out at summer camp in 1991. The indiscretion held for eleven years, until the kid, then 19, told The Hartford Courant, and the story was picked up by the AP.

The Bersteins' explanation has always been that their boy got the story from his mother, Nora Ephron, who was merely guessing. (Good account of that who episode here. A few more eyebrows were raised when Bob Woodward made a trip to see Felt shortly afterward. Some speculated that he was there to see if it was time to give up the secret. Looks like they were right.)

Second Update:

You can read the Vanity Fair piece here.