Bob Woodward writes the definitive, 4,882-word account of how he came to meet, befriend, and collaborate with Deep Throat, aka Mark Felt. The Post obviously gave Woodward carte blanche on the piece, which is first-person and filled with small personal details. But God is in the details and it's a fascinating account, and presents a very real and fleshed-out picture of Mark Felt when he was Deep Throat and not a 91-year old man bending to the will of his family (more on this later).
As you can see, the story jumps off the front from a fairly modest space (to my mind, for the stature of the story and the storyteller), but maybe that's because yesterday's front page was dominated by Deep Throat. There's a great archive of that coverage here (with a VF cover page shot as a special bonus). The Post also has a complete Watergate chronology here, including front-page shots and links to key stories.