Marc Ambinder caught this last night:

CBS News's Jeff Greenfield and I each have independent Democratic sources who say that an advance team for Barack Obama is in Richmond, VA preparing for a campaign event next Thursday.

To conjecture, of course, would be easy. Gov. Tim Kaine lives and works in Richmond... but
Virginia's a swing state; it's not unusual for Obama to campaign there. Or maybe it's an event for Michelle Obama.

As Ambinder notes, whatever is going on in Richmond, Obama has to be getting close to his announcement. If he doesn't do it next week, then it'll be a convention-week announcement, which is very unlikely.