This is a bad idea, expensive, intrusive and poorly conceived.
Here Peter Lilley makes a great case against them:
www.bowgroup.org/pub/IDCards.pdf
Specific analysis of the ID cards/NIR Bill
Information Commissioner's warning
Also note this article:
Fake gaijin [foreign resident] cards that are sophisticated enough to fool police are already on the market, just four months after the real certificates of alien registration were redesigned to outfox forgers, the Justice Ministry announced...
...It took three months for the genuine [security] seals to be produced; the forgeries, just four months. A Justice Ministry official could not conceal his surprise, saying, "We thought forgeries would appear at some stage, but not this quickly."
"The forgeries ended up being produced in about the same time frame as the genuine cards," the ministry official added... From this article
Organised crime syndicates are bound to produce forgeries of the UK ID card because the government plans for it to eventually be used to access many state services.
I heartily concur. And may I add a waste of time and resources.