Here's the deal. If you're flying into BWI, staying in Baltimore, and plan to travel to Washington by train, you'll want to keep an eye on MTA Maryland's website, www.mtamaryland.com, and hit the News link. Here's the short version:
MARC Train service will have specialty Baltimore to DC service, BUT you need to buy a seperate special Inauguration ticket. These are reserved trains -- No regular tickets will be accepted. Details will be released on Friday.
Commuter bus service around the state will terminate at nearby WMATA Metro stations. Their site is ww.wmata.com
Once again, check www.mtamaryland.com for Jan 20 details on Friday.