Everybody's doing it!
Jerrry Seper in the Washington Times reveals More countries issue ID cards to illegal aliens in U.S.:

Guatemala, Honduras, Poland, Peru and El Salvador, aware of Mexico's success in getting identification cards to its citizens in the United States, including those here illegally, have begun or are considering issuing cards of their own, federal officials said yesterday.

That should read "mostly to those here illegally". If you are in the US legally, you already have documentation and don't need this card unless you are a collector of obscure artifacts with $29 to burn.

Known as "matricula consular cards," the digitally-coded documents are being used by Mexican nationals in the United States as legal forms of identification, giving the holders the ability to apply for social services, open bank accounts, cash checks, sign lease and rental agreements, and board airplanes.

Such a deal! I wouldn't want illegal aliens to miss out on social services!

Ironically, no major bank in Mexico lists the "matricula consular card" among the official identification documents they accept to open an account, and the cards are recognized for identification purpose in only 10 of Mexico's 32 states and districts.
...
The report also said safeguards are not in place to prevent the issuance of multiple cards to the same person, noting that the U.S. Immigration and Naturalization Service already has reported finding several cards in different names issued to the same person.
...
Last week, the General Services Administration suspended recognition of the cards at federal facilities pending an investigation. The GSA said once the probe is completed, a recommendation would be made to federal law enforcement and security agencies to ensure the cards' integrity and security.

This Mexican card costs $29 and you have to stand in line down at your local Mexican government franchise, er, consulate. If you stop by the Country Store, I'll get you a card too. Only $5!