"Please note that an RFID tag will be imbedded in your registration badge and will not contain any personal data but only an identification number. The ID number and their related data collected during CES will be used for internal purposes only by Show Management and will not be sold, bartered or traded."
In other words, since vendors and journalists alike have never really taken to those swipe cards meant to gauge booth attendance, the Consumer Electronics Association has decided to track us more efficiently by making it a passive affair -- ensuring that the hours we spend "working" at the international food court will be well documented. Actually we're not all that worried about having our movements tracked as long as the data is used anonymously to tease out certain aggregate trends, and not available for Intel to find out that we spent way more time with the folks from AMD. However, some of our colleagues may not be as childishly trusting as we are, so for all the paranoid techies out there, the CEA has thoughtfully given attendees the option to opt out of the program. We'll be sure to bring you a hands on with the ID's when the time comes, along with documenting the confusion that ensues after we strap our own badges to a family of small mice, release them into South Hall, and completely wig out the computers furiously attempting to monitor the roaming nerd herds.
Update: As several readers have helpfully pointed out, the tags will likely be of the high-frequency, short-range variety -- perfect for handheld readers at the booths, but probably incapable of detecting the fact that one unnamed Engadget editor spends an inordinate amount of time in the bathroom.