The ACLU animates an amusing (and by amusing I mean eerily disquieting) vision of what a national ID database could mean, here.
Fortunately however, this month in the state-federal game of chicken over the REAL ID Act, the feds swerved first. While the bill required states to comply or file for an extension by this month, to date, at least six states have simply refused to adhere to the law–and when the deadline passed a week and a half ago, many didn’t bother applying for extensions, either.
A chagrined DHS went ahead and issued them anyway. The new deadline is now 2010. By then, a new presidency and Congress will hopefully make the whole mangled plan–passed in 2005 as a rider on a defense bill–moot.