Starting in January, biking to work could qualify you for a modest tax break (Road Worrier: "$700 billion plan offers tidbits to bike commuters").
The IRS has not yet announced rules for the addition of bicycling to what employers call qualified transportation fringe benefits programs. These programs already include (more genereous) tax breaks to defray employee costs for transit passes, vanpool fees and parking bills.
The League of American Bicyclists promises to post updates as details become available. Stay tuned.