Charging the iPhone with the iPad Charger

I learned something new this week on the latest episode of The Talk Show on the 5by5 Network.  Charging your iPhone with the iPad charger will charge it much faster.  John Gruber even joked that waving the iPhone near an iPad charger will immediately charge it. At first (when I got the iPad), I thought this would somehow overheat the iPhone, but the same concept works on the Mac.