It's not limited to cell phones, but it is limited to the amount of current you can draw through the outlet. How many amps does a Zumo use when it's powered up? If it's lower than the capacity of the outlet, then you can plug in your Zumo. The outlet is 12 volts, if it's a standard cigarette lighter style outlet; if I had to guess, I'd say it has a 3 amp capacity, but I could be wrong about that.
There are different ways of running power to your Zumo, depending on where you want to mount it. You can run a power cable off the battery (with an inline fuse for the wiring) terminating in a handlebar mounted outlet that's rated for the amperage needed for your Zumo. The handlebar outlet works good if you're going to mount the Zumo on the bars. Where were you planning on mounting it?
"No matter where you go, there you are."