Well, at least this time, XRoad kept their promise to release G-Map "in mid December 2008". As for now, a version of the western US is available trough the AppStore for the reasonable price of 20 US$.
The Screenshots also look very promising and also the feature list is neat. Unfortunately, there is no demo version available at this time. On G-Map's support site, there is a web form that has a dropdown list which mentions US east and North America, so those are likely to be released very soon.