I'm specifically looking for one that lets me display a map of US states with each one as it's own "object" in the sense that I can control the color, on click, and on mouseover of each one individually.  GTK is my personal preference, but at this point I'd settle for just about anything.  The application itself will be written in Python, FWIW.
If you consider Qt, consider also throwing in kdelibs dependency, then you'll have marble widget, which handles maps in neat way.
If you stick only to Qt, then QGraphicsView is a framework to go.
(note: kdelibs != running whole kde desktop)
Does anyone know of a widget for a desktop toolkit(GTK, Qt, WX) for displaying a map of US states?