I just found this via the ilounge rss feed and it answers the question I’ve been asking myself for a while now about the value of the 3G iPad vs the Wifi only model.
Up until now the only real missing feature for me on the Wifi iPad (on order!) was the GPS. Not that I have a decent way of mounting it in the car yet, but that should make for an interesting DIY project. But the question remained - if I wanted GPS connectivity, I needed an external GPS and as it happens I have the TomTom car kit that I use with Navigon on my iPhone. Unfortunately the car kit is very precisely designed to hold an iPhone and not an iPad.
Now with this cable, I can easily connect the car kit to the the iPad, no matter what bizarre setup I end up using to mount the two at the same time.
This also opens up the whole collection of iPhone specific docking devices that can’t be used with iPads because the form factor doesn’t work. Finally!