The eight-pin footprint next to the FCC logo is the VideoCore JTAG connector. The connector isn't populated, but the signals are all there and usable (AFAIK).
The accelerometer and temperature sensors / settings could make it a little more difficult, since the heat sink is directly above the processor and one would need to get through it to gain access to the pins.
But it could be possible with some creative solutions. Probably not if all tamper protections are active though.