I can confirm this:

Cig lighter adapter with USB port and generic micro USB cable doesn't work with my n900. Not sure if the nokia cable works in cig lighter port yet, will try tomorrow. Is there such a thing as non-powered micro usb cables vs. powered usb micro cables? If so that could be the issue as I know other devices can be picky depending on the cable. I would like a fix for this also, or at least know if we need to buy nokia cables exclusively.