Ok, so skimming through this, I find it hard to believe no one decided to bring up the actual usable range of these chips.
The idea of someone using a chip this size to "track" you is just plain ludicrous. I researched RFID tracking for a paper I wrote a couple years ago. The effective range of the "chip" is very small. We're talking in the feet range... no that's not tens of feet range. That effective range is further based upon the size of the chips antenna array. Take a credit card sized array (yes, you can look at that card labelled "paypass" if you wish) The effective range on that card is suppose to be 3 feet. With a RFID Skimmer (costs about $98 to make one) that far, FAR exceeds FCC standards, you can boost that to about 10 feet to reliably read the information off that card. I dont think anyone would be willing to run an antenna the size of that credit card in their bodies. These human chips are more in the centimetres range.
As it's been said before, most people have cell phones, that's how they will track you. The chip could actually save lives if used properly and responsibly (Replacing MedicAlert bracelets for instance) Sure the medical data server COULD be hacked... but seriously people, those records are already on that server and at risk, so what's the difference really?
I seem to remember a similar conversation when barcodes were first introduced. (Mark of the beast and all that) Now barcodes are common place, in fact my store which fixes computers would be seriously inconvenienced with out them.
Can technology be used for evil, sure. The only thing bad from this I see is custom tailored ads. Come to think of it, that would be not such a bad idea. Any one watch minority report with their morphing screens that show ads more relevant to who ever is in range? Think of a website where you could log in, enter the code that your RFID has and tailor those ads to you? Better yet, if you could pick your own ad (mine would be a blank screen).
EDIT: Found my source images again.
This is the credit card sized antenna, after microwaving to make it visible.
This is the one that was approved for people. (That's also on their LEFT hand, not right )
Sorry the links are big.