Ansuz82 wrote:
Exactly. The older ones put out up to 12v.
There's so much misinformation around! The older USB chargers were 5 volts. Only the Firewire chargers were 12 volts, but USB cables will not fit into a Firewire charger. The size of the adapter doesn't matter, as long as it is USB. All USB adapters, from any manufacturer, put out 5 volts. It's a world-wide standard.
According to the Apple support site you can use a Firewire charger with a iPhone also (regardless of what a Genius says). However, there is enough anecdotal information around that it might cause the phone to overheat, so I won't try it.