Originally Posted by Apache
They may claim that (I know they used to), but it isn't true. The reason they discourage it is that the computer only puts out the specified amount of power through a USB cable, where the wall charger puts out more, and therefore charges it faster. (If you compare the cable end that goes in to the device, you'll find it's longer than the standard ones, to make a connection to the charging circuit that handles the higher amount of power.)
I believe the device will also claim to not be charging in terms of the light on the cable end and the batter indicator. But it will charge, eventually.
You have to have the screen off, too (since the NC apparently pulls more than a half an amp - USB spec - with the screen on). With the screen off it will trickle-charge.