I, too, am skeptical of a national ID program, wondering just how it improves upon the 50 state driver's licenses it would replace as your "papiers" when you travel; OTOH, I find it TOTALLY offensive for others to criticize (as in the critical comment to Nobby, above) based on what other countries do. It is RUDE if nothing else.
Our system including our constitution(which I support and defend) is pretty good, BUT it's only one way of doing things. Those that hold it up as immutable seem to fail to recognize it was written in an age when today's problems were undreamt of. That said, this whole thing of a Federal ID system being "unconstitutional" is a canard: #1, plenty which was "unconstitutional" in 1933, including Social Security and a minimum wage, are today considered "constitutional", as the court changes and somehow accomodates societal need. And #2: Let's figure out what it would take to REALLY improve security in ways that are meaningful, and THEN discuss whether a replacement ID is the best idea. Nobody has yet convinced me that a federal ID is better than my CA driver's license (although I remember when NY DLs had NO picture.... perhaps this is still the story somewhere). Finally, #3: It is revealing that we as a society see fit to let this scare us into "founding fathers" arguments: perhaps a more rational debate would be served merely by focusing on what it would take to assure our security, AND let us maintain our freedom AS WE practice it today.
Just one person's opinion.