With the stock 320andup download, when you rotate an iOS device to landscape the viewport snaps out much larger than needed, rendering the output larger than the screen. Even when you load the page in landscape, rotate portrait, then landscape it still snaps larger. Is this the expected behavior? Confirmed with the 320andup site.
It's an iOS thing, rather than a 320 thing. Arguably it's a bug in mobile safari but there are possible reasons for it happening, i.e. keeping the same relative position on screen, regardless of size. There have been bug reports of it I believe but there's not a great deal you can do about it (or there wasn't last time I checked).
A bit more information here: http://filamentgroup.com/examples/iosScaleBug/
Apparently its caused by initial-scale=1.0