Drive-by-wire means there is no mechanical linkage between your gas pedal and the throttle body. Instead you have a gas pedal wired directly into your ECU which then sends signals to your throttle body.
Acura this year is fronting the drive-by-wire technology extensively for most of there model lineup. If you go to there website, they explain how it was first develop for there formula 1 engines for racing purposes, because it gave them more accuracy and responsiveness, improving power delivery, fuel economy and exhaust emissions. Pretty much all German cars use it. Its new technology and I'm sure given enough time, pretty much all cars will have it.
My '04 has it, but the only thing I don't like is that the gas pedal is so damn sensitive. You just press it a tad and it revs up so much, I've only driven cable throttle cars before, so it took some time to get use to. But once you adapt to it, you'll notice how the car responds instantly to throttle inputs, I think it works really well.
But damn Power FC doesn't work with it.