Here's an explanation at
http://www.louisville.com/loumag/mar/bacon.htm
Excerpt:
"Three years ago a trio of Pennsylvania college boys with too much time on their hands and a bottle of Southern Comfort came up with the game Six Degrees of Kevin Bacon. Craig Fass, Brian Turtle and Mike Ginelli wrote a letter to then TV talk-show host Jon Stewart, who invited them on his show to demonstrate the game. From these humble beginnings, a Web site arose, a book was published and a nationwide cult-fad was born.
The game is based on the conceit of the John Guare play and movie adaptation Six Degrees of Separation. The play posits that we are all connected by six or fewer stages of circumstance or acquaintance. In other words, if I were to run into Elvis in the Grant Line Road Kroger store's produce department, we'd hardly be to the dairy case before establishing that he was in King Creole with (1) Dolores Hart, who was in Where the Boys Are with (2) Paula Prentiss, who was in Catch 22 with (3) Richard Benjamin, who was in a remarkably brief TV series, Quark, which featured (4) the Barnstable Twins, whose grandmother, (5) Ellen Haverly, gave a pressure cooker to (6) me as a wedding present. Voila! Only six degrees separate the King and me!
Fass, Turtle and Ganelli took the concept one step further (or back). Noting how nicely Kevin Bacon could substitute for "Separation" in the meter, they hypothesized that he might also be the center of the universe, at least when it comes to connecting actors.
Although never a big box-office draw, Bacon has been in a significant number of ensemble films, from Diner to Apollo 13. And the boys discovered that if you use Bacon as an end point, you can link him in six degrees or less to almost any other performer." <snip>
BTW from what I remember reading, Mr.Bacon is less than thrilled to become a part of cultural trivia. Can't say I blame him.
[This message has been edited by Auburn Annie (edited October 21, 2003).]
but what is a bacon #? 
