I generally consider myself to be a privacy advocate. I believe the right to privacy is one of our hard earned rights as American citizens, and I don't like the idea of giving up any of my freedom. On the other hand, I do agree with Tone and the others who've said that those who have nothing to hide have little to lose by these types of technologies.
The new bill, as I understand it, is not exactly a national ID card --- it standardizes some of the features of state ID cards so that they can be universally recognized. The only thing that is really being added for sure is a national ID number (the equivalent of a SSN), a universal electronic scanning method (mag strip or possibly RFID) and possibly a biometric like a fingerprint.
The electronic scanning is what I think bothers so many people because it makes it easy to collect data on individuals easily and electronically. I do object to the idea of RFID scanning because that gives people the ability to collect your information without you knowing. This is a BIG deal. The idea of a mag strip or bar code or other electronic scanability does have some potential privacy consequences because it allows others to easily collect and store your information. Of course, laws could be written to prevent certain people from collecting or storing certain information, which would probably be a good idea, but this is unlikely to happen because that's how the government would track the criminals.
I think a lot of people are making jumps that don't need to be made right now, but maybe some of these things are inevitable. Once the technology is there and accepted by the public, it makes it so much easier to move into all these other technologies that would violate our precious privacy.