From what I understand this is a tax credit, not a true subsidy - so you don't just get $25 for riding your bike. If you are a business and you provide some kind of benefit for employees who bike (like showers, a bike cage, a commute bonus, etc.) then you get to deduct $25/month/rider from your pre-tax income. That means that even the business doesn't get $25 - they get whatever percentage of $25 that their tax bracket determines.
I'm kind of with RoadBikeRider... I don't think that this will encourage many businesses that are not already providing incentives to start. It will benefit the ones that already do.