Once upon a time, a new science fiction drama called Star Trek premiered with an episode called "The Man Trap" rather than the pilot (actually the second pilot, the one that introduced Captain Kirk) on September 8, 1966. The pilot, "Where No Man Has Gone Before," wasn't shown till the third week on the air. NBC's decision to switch the episodes didn't help amp up Star Trek's ratings in that first season, but network wisdom at the time was that "Man Trap" was a better starting point than "Where No Man Has Gone Before."
Cut to now. Two current properties, CBS's Eleventh Hour and Fox's Do Not Disturb, have switched out their pilot episodes for another episode as the season's premieres.
You might recall that Brett wrote a month ago about this happening with Joss Whedon's Dollhouse too.
On September 10, the Fox comedy Do Not Disturb will present "Work Sex," about the workers at The Inn fooling around on the job, in lieu of the pilot, which will air sometime in the future. This may be a sign of trouble.
It looks like someone took the effort to create a Flash player with embedded videos of many of the upcoming new fall shows. Included are clips from 
Seven greatest hand cannons in TV history
TV Squad previews NBC's new shows (part 1)
TV 101: How ESPN controls the world and what the other networks can learn from it
