  We have developed a small, neutrally buoyant, wireless temperature sensor.
Using a camera for optical tracking, we obtain simultaneous measurements of
position and temperature of the sensor as it is carried along by the flow in
Rayleigh-B\'enard convection, at $Ra \sim 10^{10}$. We report on statistics of
temperature, velocity, and heat transport in turbulent thermal convection. The
motion of the sensor particle exhibits dynamics close to that of Lagrangian
tracers in hydrodynamic turbulence. We also quantify heat transport in plumes,
revealing self-similarity and extreme variations from plume to plume.
