Intrade is making Brown a 4-1 favorite; you can buy an option for $2.50 that will pay $10 if Coakley wins. I couldn't get money into an account with this short notice, but there is no way that this isn't a great deal.
My take (to be honest, I admit I haven't a clue on this one)... but here goes,
I think the fact that this has now become such a big deal will drive up voter turnout, meaning that in Democratic Massachusetts, Coakley wins.
But then again, the fact that the Democrats control the White House and both houses of Congress in an off year election in a tough political climate could mean that the Republican can win this.
Then again the Democratic GOTV organization in Massachusetts could put Coakley barely over the top.
But then again Brown is a charismatic candidate who has pulled off the impressive trick of tapping into the unhappy tea party crowd without turning off the independents could mean he can squeak out a win.
I am biting my nails on this one, it really depends on who shows up.