From a SDUT editorial:

...Utah's action [to give "driving privilege cards" to illegal aliens rather than real driver's licenses] points to a national wave of public concern about issuing to illegal immigrants a license to do far more than drive. It's a wave, too, that will become a veritable tsunami if federal legislation that just passed the House of Representatives makes it, as it should, through the Senate. In that event, states may continue to issue driver licenses to illegal immigrants, but driver licenses from those states will not be accepted for federal identification purposes – to board a plane, for example, or enter a federal building.

[...Why do this?] Start with the fact that neither the nation nor the states should make travel easy for illegal immigrants bent on doing harm here. Driver licenses have become de facto identification cards, "breeder documents" that can facilitate further illegal acts, from terrorism to lesser crimes, by illegal immigrants. Determining the legal status of license applicants adds another check against their abuse.

And move on to the overweening fact that making illegal immigrants legal drivers rewards their illegality, encourages other illegal immigrants and further blurs the already too-fuzzy line between legal and illegal residents. Limiting driver licenses to legal residents is only one clarifying dot along that line, but one Congress and the states should endorse...