When there is software for a Foleo to be used like a RedFly device, I'd buy in. Especially if the web browser is like a desktop browser. But until then I think I prefer something that uses the smart phone as the computer.
Remember... all your data is there. Personally, I don't want to move all my data to the cloud, and I hate constant syncing with the desktop.
Plus, with a good remote desktop application and a broadband connection, you can run all your desktop apps from the smartphone via the dock just like you were using your desktop at home. Well, actually in that case you are!
As far as the display drivers, I think that some phones now, as well as the VGA Axim PDAs, include dual display capabilities. The driver is probably either not needed (if it's simply a secondary display of the same VGA output to an LCD screen) or already there with the device, or if not, it should be reasonably straightforward to create and give it better resolution than the device had originally (like the RedFly).
So it's a race... price and capabilities of Foleo or Eee type devices with accommodation of smart phones and good web browsers, versus the price and capabilities and web browsers of the smart phones themselves via a good dock and remote desktop software solution.
Either way, I'm delighted when we get there, and I can not worry so much about syncing (except backups) and have the option of full keyboard/display. Nice remote desktop software is fine for me, so the smart phone doesn't ever have to become a fully capable desktop replacement.