As much as I believe in civil liberties, I have no trouble with identification being required to fly on commercial airplanes. As  has been shown on 9/11, airplanes have the potential to be weapons, and access to them needs to be monitored and regulated.

The Justice Department says showing I-D’s at the airport promotes and protects safe travel, and an appeals
court agrees. A panel of judges in San Francisco has dismissed a legal challenge which argued that the requirement for showing identification amounts to an illegal search. Libertarian activist and millionaire John Gilmore claimed the policy also violated his right to travel freely.
But the judges unanimously ruled that the security provision is not overly intrusive. The court says Gilmore can leave the airport if he doesn’t choose to show his I-D, and that he has other ways to get around besides air travel.
Gilmore’s lawyer says he hasn’t decided whether to appeal.  via 33 News