Summary and Conclusions
To see whether HP fared any better with built-in WiFi, I tried to get an HP H4150 (which uses an Intel PXA255 clocked at 400 MHz) to include in this NTK. But after a month of intermittent back-and-forth emails with an HP PR person, HP was unable to supply one. If one happens to show up at some point, I'll give it a quick test and update this NTK.
But similar to previous spec problems with number of supported screen colors and amount of memory that you can actually use, it appears that PDA manufacturers have also put consumers in a "buyer beware" position when it comes to PDA wireless speed.
One might argue that the speed of a PDA's WiFi connection doesn't really matter much as it does for a notebook or desktop, given PDAs' more limited uses. But with Sprint pushing its 2 Frames/sec MobiTV service on cell phones (!), demand (or supply) of streaming video to WiFi-equipped PDAs probably won't be far behind. Network admins trying to run remote desktop and network management apps from a PDA can also use as much speed as they can get.
So the need is there, but unfortunately the supply of full-speed WiFi PDAs is somewhat spotty. Caveat emptor is the watchword and unfortunately, buy, test and return the only practical solution until customer demand and competitive pressure gets vendors to deliver the goods that they should.