UPDATE: 8/21/2012 3:30 PM
It looks like the main source for the September 8th season 7 U.S. premiere date came from a recent BBC America "Doctor Who" trailer. BBC and BBC America have yet to confirm the date that appears in the video.
UPDATE: 8/22/2012 9:30 AM
BBC America has confirmed the September 1 airdate for both the US and UK.
All summer long, BBC has held back on the release dates for "Doctor Who" season 7. But now, the Doctor will see you in September.
Fans in the USA and the UK will reportedly be able to see the seventh season of "Doctor Who" on Saturday, September 1 on BBC America and BBC One.
However, fans in the US will have to wait until Saturday, September 8 to see the premiere on BBC America. Presumably the delay was arranged to keep "Doctor Who" from airing on BBC America during Labor Day weekend.
Earlier this week, BBC released a teaser trailer for the first episode of the season, "Asylum of the Daleks," which offers a few hints about what's ahead for the Doctor (Matt Smith) and his friends.
BBC has also released a fairly spoiler filled synopsis for "Asylum of the Daleks," so consider this your SPOILER WARNING before reading further!
"Kidnapped by his oldest foe, the Doctor is forced on an impossible mission – to a place even the Daleks are too terrified to enter… the Asylum. A planetary prison confining the most terrifying and insane of their kind, the Doctor and the Ponds must find an escape route. But with Amy and Rory's relationship in meltdown, and an army of mad Daleks closing in, it is up to the Doctor to save their lives, as well as the Pond's marriage."
Six episodes (including the Christmas special) of "Doctor Who" season 7 will air this year, with the remaining 8 episodes to be released in 2013.