If you open up your oyster card, you’ll find the same (tho with a larger antenna) – same with a swipe card for an office, or one of those touch-to-pay visa cards that barclays insist on giving out these days.
The actual chip is the darker bit in the top right corner. The rest is just antenna / induction loop.
could be interesting to program / clone one of these onto a Google Nexus S, which has RFID in it…. rumer has it that the iphone5 might have this in, but I doubt it for a while