I'm a contractor at one of the DOT Agencies... and I've been bike commuting to DOT HQ a few times a week for the past 3 months.
I come into DC from Arlington via said bike paths and when i-395 is a mess, it can take an hour to get into work. Without traffic its a 15 minute ride, but there's always traffic. Its just 35 minutes out and 45 minutes back on the bike with ZERO emissions.
If you've ever had the pleasure of working for our Federal Government, you wouldn't be surprised at the wonder generated when you tell others that you rode your bike into work.
In the DC Metro area, it just shows your dedication to your job (and/or insanity) with how much of a commute you can put up with. Me, I wouldn't live in the burbs like many of my co-workers... the commute would drive me insane.
There are some enlightened folks in DC however. The new mayor is set to require a ration of 1 to 10 bike parking to car parking in all city buildings. A small, rental fleet of cycles is due to launch soon in the District. Arlington is set to do the same with a larger fleet of bikes.
Bring the next critical mass to the Soufeass Waterfront instead of Dupont ;-)