In theory, you'd be able to use VNC as-is. For PalmEmpeg to work, I think you'd have to wait for a software update that supports tcp/ip as well as serial.

Not sure how well the Hijack's web interface would look, but when the XML & XSLT group comes up with a plan and mlord impliments it, then you should be able to make something that works well on the Visor.

With the cheap Visor Neo and the (not so cheap) Xircom Springboard 802.11b adapter it'll run you about $470. You end up with something that fits in the palm of your hand, is customizable, has a very long range and can make instant changes to your A/V system. You can get each of those features cheaper, but I don't know of any other way to get them all in the same package.