So after all the rumors and wild speculation, it looks like Obama will make a very conventional week-before VP announcement. From the Politico:

Senator Barack Obama is expected to choose his running mate this week in a key decision about the direction and narrative of his bid for the White House.

A person familiar with the campaign's planning noted that Obama's schedule at the end of this week is open, but said the announcement could come "as late as the weekend."

Obama and his inner circle have held his intentions tightly, while a wider circle of aides in Chicago has been kept far enough out of the loop that they're willing to speculate freely on the possible choice.

As with McCain's expected post-convention announcement, this is the smart move for Obama. There are probably good arguments for and against waiting until the weekend, but in the long run it won't matter much. Obama will own the coverage next week and when he decides to take ownership is up to him.