I did a bit more research, and the Tungsten E also looks like a good bet for development. Like the iPAQ 3600 series, the Tungsten E looks like the lowest common denominator in Palm devices. The slow processor, basic 320x320 screen, 32MB of memory and the $199 price tag makes it a good starting device to target.
That brings up another question for Johan: What Palm devices has GD3.01 been tested against? I certainly don't want to run out and purchase a device only to find that GD won't run on it.