I actually have a citizen card, its for proof of age - not nefarious govermental schemes.
I got mine so that I could take domestic flights without a passport, and as I dont have a drivers license, I can use it as ID at the bank to prove who I am.
Its actually a very useful thing to have, especially for students etc (I got mine when I was a student). You can read about it here:
http://www.citizencard.com/ - dont worry, no one will try and subvert you if you visit that page.
As far as a precursor to the ID card goes, it would be pretty lame as it doesnt really hold any data on you apart from your name and DOB. You need a reference to prove your name as well as a copy of your birth certificate but thats it.
And retailers asking for ID now in the supermarket? Maybe thats to enforce the over 18 smoking law as well as to enforce the over 18 alcohol law. Which, by definition, are both good things.
I am going to go out on a limb and say that the govrnment doesnt care if I bought some onions on the way home last night - and didnt show my ID card in the process