Not a search, apparently. Brian Doherty has been covering the Hiibel case, which challenged the right of law officers to demand identification from citizens without probable cause. Privacy advocates argued that as more and more of our lives are indexed and cross-referenced in ever larger and more expansive databases, your name and ID is a key to such a large cache of information that requiring it to be supplied should count as a "search" within the scope of the Fourth Amendment. Today, in a narrow 5-4 ruling, the Supreme Court disagreed. The full opinion is here in PDF form.