AP has called it for Brown.  Coakley has called Brown to concede, according to Rachel Maddow on MSNBC.

Roller Coaster!  Chuck Todd at 5:39 pm Pacific time:

17% in: Brown (R) 52%, Coakley (D) 47%. Just four precincts have reported so far.

Gap widening again.  Chuck Todd at 5:32 Pacific time:

11% reporting: Brown (R) 143,950 votes, 53%; Coakley (D) 126,037 votes, 46%

Coakley moving up slowly.  Countdown on MSNBC reporting

Brown 51.1%, Coakley 48.1%

Chuck Todd at 5:29 Pacific

7% reporting: Brown (R) 69,627 votes, 51%; Coakley (D) 65,533 votes, 48%

According to Chuck Todd's tweet at 5:22 pm Pacific:

4% reporting: Brown (R) 30,579 votes, 52%; Coakley (D) 27.551 votes, 47%

I will continue updating as often as possible.