Earlier I reported that bike commuting was way up in DC, from 3.2% to 4.1%. That's true. But when looking at the other modes, it appears that the increase almost entirely came from transit.
Here's year to year data
Mode 2011 2012
Driving 39.6% 39.7%
Transit 39.6% 38.6%
Walk 11.8% 11.9%
Bike 3.2% 4.1%
Other 1.1% 1.0%
Tele 4.8% 4.6%
The only modes that saw much change were biking and transit. That doesn't mean it's a wash. Biking has advantages such as health and congestion mitigation that transit may not have, and moving people off of transit helps to deal with crowding and allows for delays in buying new vehicles. Furthermore, in DC it may make more room for suburban commuters so that total transit use doesn't drop much. Still, it would be better if biking were moving people out of cars.
Also, both Maryland and Virginia had 0.4% bike commuting state-wide, up from 0.3%. PG County was at 0.3% putting it below the state average.
Update: It's also worth pointing out that this survey is done in April. So the 2011 data would not really include the uptick in biking from CaBi yet. The 2012 data is the first real post-Capital Bikeshare data.