I'm late to the party but I just got an iPad. The touch interface is a wonderfully intuitive way to interact with maps. The iPad runs Google Earth beautifully and there's a great mapping app called MotionX that lets you download NOAA ENCs for offshore navigation.
I would LOVE a Global Mapper app that has the ability to display a gmw/gmp pair and use the built-in GPS to overlay position. I would buy it if it only went that far. If it could save track logs and calculate navigation (course & direction with a steer arrow) it would be even better. I'm not really interested in "working" on the map from the iPad. I'm happy preparing a package on my desktop and just displaying it on the iPad when I'm on the boat. I've paid $30-$45 for other hobby or work specific apps so something in that ballpark wouldn't be unthinkable.
Anyone else interested in viewing their GM maps on iPad?