State Sen. Joe Simitian (D-Palo Alto) called his legislation a safeguard against "the ultimate invasion of privacy." Gov. Arnold Schwarzenegger signed the bill into law in October.
Virtually all leading cellphone makers are already introducing this technology to their handsets. Payments by cellphone are expected to explode over the next few years as more stores are equipped to handle such transactions.
Here's how it'll work: You go to the Gap, select a pair of khakis and wave your phone in front a reader at the cash register. The purchase price is instantly deducted from your checking account like a debit card or applied to a credit card account. A record of the purchase is also entered into the Gap's database.
That's very convenient and will undeniably be a boon to shoppers, merchants and cellphone companies.
What the technology also means, though, is that all cellphone owners, which is nearly everyone, will be technologically "tagged." In theory, anyone -- or any company or government agency -- with a desire to do so would be able to identify you from as much as 300 feet away and track you as you go about your business.
Your cellphone would be constantly broadcasting your location, along with, possibly, your name, address and other potentially sensitive information.
"The public has been slow to appreciate the privacy implications of this technology," said Simitian, who has a variety of other bills in the hopper to address various aspects of what's known as radio frequency identification, or RFID.
"Most people don't realize that there's no law against who can read the information on an RFID tag, and no limit on what can be placed on the tag," Simitian said.
OK, let's take a deep breath. RFID technology has been around since World War II, when transponders were placed in Allied aircraft to distinguish them from German planes. These days, RFID is everywhere.
When workers wave an ID card or fob in front of a reader to enter their office building, that's RFID. When plastic tags are placed on merchandise in supermarkets or retail stores to manage inventory, that's RFID.
RFID tags are starting to be inserted in driver's licenses and passports. The Legoland theme park in Denmark recently experimented with giving RFID wristbands to kids so they could easily be found by parents. (A spokeswoman said there were no plans to test the technology at the Legoland in Carlsbad.)
China is now in the process of issuing RFID-equipped national ID cards to all of its 1.3 billion citizens.
There's no question RFID can make official documents harder to fake and make life much easier for consumers. Think how fast a checkout line would move if everyone was carrying an RFID-equipped cellphone or credit card instead of cash or old-fashioned, magnetic-stripped plastic.
Cellphone companies love the technology because they anticipate customers using more minutes and being less likely to switch services once they've turned their handset into an e-wallet.
"Everybody's interested in this," said Mark Desautels, vice president of CTIA -- The Wireless Assn., an industry group. "There's an awful lot of experimentation taking place throughout the industry."
IDTechEx, a market researcher specializing in RFID, estimates that more than 2 billion tags will be sold to companies and governments worldwide this year, compared with 1.7 billion last year.
The number of tags in circulation will be 300 times larger a decade from now, the firm estimated, citing rapid reductions in RFID costs and expansion of the number of RFID scanners at businesses and government agencies.