Lots of questions already piling up for Ask Me Anything Day! "DC Observer" asks:
Who are the early Democratic frontrunners to challenge Brown in 2012?
Do you see a member of the Cong. Delegation? A former member like
Meehan? Someone from state politics? Private sector?
I think that Meehan is very likely. A congressman would have to give up his seat to run, which seems unlikely unless the GOP really does take over the majority in the House (and looks likely to keep it after 2012), although a couple would be sorely tempted. It's also possible that redistricting will endanger one of them, making it more tempting to jump into the Senate race.
I would also look at Bill Galvin, Alan Khazei, Steve Pagliuca, Tim Murray (especially if Patrick loses this year), a couple of state senators, and I'm sure plenty of other possibilities. Expect the field to start forming immediately after the November 2010 election.
Update: I totally forgot about the Kennedys -- Vicky is a strong possibility. I'm not sure anyone else in the family would go for it, although I suspect they and their circles will be pressuring one another to do it.