Some comments on RFID tagging...
Seems some posters have alredy picked up on the RFID tagging that could be used on firearms and gunpowder. I would -highly- doubt that's going to happen, and if it does they're easy to defeat.
First, RFID tags are just passive devices. They don't power themselves and have no capability to store information regarding where you've been nor do they actually emit any signals. When hit with a radio signal of the right frequency they do radiate back their ID number -- and that's all they can store -- a single number. Last I heard they are now able to make 128 bit RFID tags for just pennies which is big enough to tag just about everything in the world with a unique number. 128 bits of storage gives you 2 to the 128th power possible numbers which is:
340,000,000,000,000,000,000,000,000,000,000,000,000 and change.
RFID tags are easy to disable too. They're fragile radio devices and something like a microwave beam will destroy them. Remove gunpowder from original packaging, place it into a different container, toss the original into the microwave and nuke it. Discard.
They're passive, which means that you have to hit them with a signal to get a response too -- and that's not something that can be done at long ranges. The power required to get a response from one increases exponentionally (I beleive by a power of 2) as the distance increases linearly. If it takse 10 units of power to get a response at 2 feet it takes 100 at 4 feet, 10,000 at 8 feet, etc. It becomes impossible to get a good reading off anything at any real distance.
This does work though if scanners are place on roads. I beleive one company (Michellen?) wanted to put them in tires and scanners on roads so that people could be notified if their tires were recalled or something like that. Thanks, but no thanks.
For the truely paranoid one could build a HERF (High Energy Radio Frequency) gun to disable any devices that they think might be carrying an RFID. They're similar in nature to an EMP (Electro Magnetic Pulse) device but directional and fairly easy to build if you've got a decent backgrounds in electronics. I'm not sure of the legality of constructing a device but there seem to be a number of science minded guys out there on the web that have built them with nice instructions on how to do your own. I kinda want to build one sometime to see how much havok they're capable of (on my OWN property -- I'm not going to go disabling street lights or anything)...
Food for thought. The rest of the projects in there kinda scare me - but RFID not so much.