iPod Chargers Question

There's some tricks.. Some older iPods will work on any USB (+5V) source..others require that the D+ and D- pins in the USB plug are tied high,or low through a ~10K resistor (i don't remember the exact details)..and yet newer models,like the 2nd-gen Nano I have here won't charge with any type of "dumb" USB port. It needs an actual USB host to negotiate power requirements with... no host,no negotiation,no charge.

Interesting. I wondered the same thing about my Blackberry phone... I can plug it in to a computer's USB port, but unless there is BB device manager software installed on that machine, I get "insufficient charging voltage available" although I can still access the device as a removable device, i.e. I can do everything but charge it.