The 12th on the 4th?

That's the 4th of August - this Sunday. Stories suddenly doing the rounds that we are going to get the announcement of who the 12th Who will be in a special live show this weekend. No official word on this, and someone may simply be taking a few happenings and merging them into this.
The BBC is supposed to be making a pilot for a new TV series that looks at long-running shows, the first being Doctor Who, this being Anniversary Year. Zoe Ball is presenting, and fans applying for tickets were encouraged to dress as their favourite Doctor / companion. Someone has started a rumour that instead of a recording, the show will actually be broadcast live and feature the announcement and interview with the new (wo)man. If bookies are correct, however, it is going to be Peter Capaldi.
As I said, not an inkling of official sanction on any of this. People are assuming that the announcement will come this month - as they start filming the Christmas Special shortly. However, the new Doctor's scenes could be filmed separately much closer to transmission. On July 29th Marcus Wilson tweeted "Okay Christmas. Here we go!" - implying he, at least, has turned up for work. From what I can gather, Matt Smith is still in California.
If this thing happens at all, it will be on BBC 1 at 7pm. Don't be too disappointed if you set the recorder and only get the repeat of Celebrity Mastermind that's currently in that slot...