Quick update - check out Mach5 browser
If they only offer "VGA" and "QVGA", I'd say they haven't tested it on a 320x320 device, since it's neither. VGA is always 640x480, and QVGA is 320x240.
I agree... I have no intention of subscribing to a browser. I'd have been quite happy to pay for a production version of Iris.
Perhaps Dorothy will be the answer...?
I think the Dorothy docs do say that it's beta, and currently 800x480 only. You need a new phone!