Do computers charge things plugged into them?

Question

Do computers charge things plugged into them?
In this case, its my Garmin Nuvi navigationGPS. To load pics onto it, you just plug into the USB port. After I was done, it appeared the battery had charged. Is this really happening? It sounds like iPods work this way? If this is the case here, is this a good method to charge the units battery? If so, that is freakin sweet because it means I wont have to buy the AC adapter! Thanks!

Answer

yes, depending on what it is and what type of cable