SunSpot is Sun Microsystems’ technology program for small, wireless sensors for many applications. Here’s a recent example from their web site documenting different applications of the technology – think about this as how easy to actually build something that can tell you more about the world around you.

“So starting Friday morning, we built a rocket, embedded 2 Sun SPOTs in “Space Shuttle” vehicles, wrote the ground-telemetry software (in Java), developed some Sun SPOT antenna extenders and documented the whole thing from start to finish. The result? We launched two (redundant) Sun SPOTs on a single rocket that streamed light, temperature and acceleration data live over the radio to the ground stations that were busy plotting the data.”

http://blogs.sun.com/davidgs/entry/the_birth_of_the_sun