I don't know about nanochips, but RFID technology is already here, prevalent and being used all over the place, it's probably in your jeans and your shirts already. I also believe the EU already has RFID in cash currency.
I can see drawbacks to having your personal info being compiled, but in order for this to be really effective you need as many monitors/police as you have citizens being watched, so what does it really mean? I think it's more going to be used by corporations to market at you. They do a pretty amazing job already of knowing who you are and where you will spend money based on some basic spending habits, this would just give them a more complete profile of you. If the gubmint really wants you, they'll get you and they don't need spending records to do it.
Besides how careful are you in your online habits? Networking sites and shopping sites expose you more readily than just about anything else...
That said, I still paid cash for my Disinfo books.