Zumo and BMW speakers

Have I missed a thread or has anyone been looking at hooking up their Zumo GPS to the speakers in the stock position. I don't have the radio ready set-up but if there is a way to use the GPS and hooking up speakers I may have to do it. It would be cool to hear the girl with attitude giving me directions plus hearing music coming out of the speakers as well. I would imagine in the future they may make the GPS incorporated into the whole system that won't be stolen as easily as is common with the GPS we have now.