I just signed up for CES 2008 today and noticed something rather interesting. It looks like the registration badges will have an embedded RFID tag. According to the website the tag won't contain any personal information, rather it will only have your ID number.
If you're paranoid about Big Brother tracking your every move at the event (that is if you're planning on attending) you do have the option of checking a box to not have one in your badge. I'm going to have one in mine, I doubt that we'll actually even notice that anything is going on with it, as it's just going to track overall info for the show management.