A new preview clip was released as part of the "Doctor Who: The Ultimate Guide" special that aired on BBCA tonight. The clip is available in the player below:
A few things are clear in this clip. As has been speculated in our house, this is not River Song's first meeting with the Doctor; she's still ahead of him, and knows more about him than he does about her. Also, she knows her way around the TARDIS, and can fly it more smoothly than he can.
This leads to the positively glorious result of the Doctor attempting to imitate the TARDIS's wheezing vworp noise as Amy looks on skeptically. Turns out that the TARDIS isn't supposed to make that noise, and does so only because the Doctor leaves the brakes on. This would seem to indicate that if the Doctor started flying the TARDIS more efficiently per River's instructions (and we've already seen him snap the doors open in The Eleventh Hour), the TARDIS mights stop making the vworp noise altogether. This would be a tragedy of the first order, but given the Doctor's affirmation that he loves that "brilliant noise", hopefully he'll keep leaving the brakes on!
Continuity note: When turning on the blue stabilizers, Dr. Song reaches for the button with her left hand around the console, but in the next shot (a closeup) she pushes the button with her right. Clearly, I've just watched this clip too many times now.