From a MTA email:

July 28, 2009 3:12 PM

Brunswick Line–Expect major delays this afternoon due to disabled freight trains, trackwork, and trees across the tracks.

Train 873 (3:35 departure) and 891 (3:50 departure) will hold in Union Station until an update is received from CSX.

Metro will honor MARC tickets on the Red Line.

Update:

July 28, 2009 3:44 PM

Bruns: MARC trains are continuing to hold in WASH, CSX track maintainers are clearing trees off the tracks and CSX is working to get disabled freight trains back on the move.

UPDATE 2:
After much needling on this blog and by Michael Dresser, the MTA website actually indicates there is a major disruption for MARC (the same goes for the email at the top of this post.)

UPDATE 3:

July 28, 2009 4:14 PM

Brunswick Update–Trains continue to hold in Washington due to two disabled freight train and downed trees blocking the tracks. Again, there is no estimate of delay at this time.

Washington Metro will honor MARC tickets on the Red Line tonight. Passengers going to Kensington, Garret Park, Washington Grove, Gaithersburg, Metropolitan Grove, and Germantown should use Ride On bus service. MARC tickets are honored on Ride On. Other passengers stand by for further information; we are attempting to arrange alternate transportation.

UPDATE 4:

July 28, 2009 4:26 PM

Bruns: CSX is allowing Marc trns 873 and 891 to depart Union Stn, these trains will proceed to Silver Spring to help alleviate Union Station terminal congestion.

UPDATE 5:

July 28, 2009 4:29 PM

Bruns: CSX has cleared MARC traffic to proceed westbound to their station stops. Trees cleared and MARC trns to operate around the freight trains.

UPDATE 6:

July 28, 2009 4:31 PM

Bruns: Marc 873 operating 50 mins late, 891 operating 35 mins later and 875 operating 20-30 mins late.

Update 7

July 28, 2009 5:08 PM

Bruns: Marc 873 60 mins late Gaithersbg, Marc 891 50 mins late Rockville & Marc 875 25 mins late kensington.

Update 8:

July 28, 2009 6:15 PM

Bruns: Marc 891 60 mins late near Monocacy, Marc 877 30 mins late near Boyds, 893 25 mins late Rockville

Update 9

July 28, 2009 6:15 PM

Bruns: Marc 879 is operating approx 15-20 mins late in the Kensington area

UPDATE 10

July 28, 2009 9:15 PM

Bruns: Marc 883 is operating approx 27 mins late approaching Harper’s Ferry.