Of the solutions you mentioned, none of them appear to give you direct access to the MapKit framework introduced in OS 3.0.
As the Google Maps HTML widgets aren't nearly as good as MapKit (see Google Latitude for an example), you are probably best off developing a native Cocoa touch application, or choosing a solution you can extend to add MapKit integration. PhoneGap is extensible in this manner (it's open-source so it is by default), and some of the other solutions might be as well.
edit: Titanium now has support for MapKit
