Okay, so, the iPhone 4 camera is a BIG improvement in detail & resolution from the 3G - not a big surprise there, really. But, note to self, using the built-in HDR function actually does take several exposures and stack them - so on windy days, things move, and you get ghost images of branches & things like that.
Or better still, the camera moves, and you get ghosts of everything! (Must try that, actually…)