This might not be especially helpful to you ATM, but
TeradiciTeradici based products are shipping at the end of this month.. probably widely available just after the first of the year. I think eVGA will be the first OEM to market..
Teradici's PC-overIP technology is pretty cool. It's basically what I have felt RDP/TS should have been 5 years ago. Complete hardware offloading of the audio and video (+usb, etc) from a PC host into an IP network. From BIOS boot to full PC session your remote session looks exactly like you are local to the PC. Can even do games on it believe it or not. Their chip pulls the video card's data directly from the bus, acts as a USB controller, high def audio device, and sends it all over it's own dedicated 1GbE port. Zero host processing.
I think IBM and Dell are now (or about to) ship blades with their host chip. But via eVGA I think you'll be able to get PCIe host cards that will turn any PC/server into a remotely controllable system.
From what I read, Teradici only has a 1:1 product right now.. meaning the host card only provides KVM like functionality to a single host session. But they are working with VMWare to implement support for lots of sessions.
Rumor on some virtualization forums suggest Teradici is planning a 8,16, and even 32-way host card.. meaning, one big bad server can serve 8-32 remote clients with dual monitors, usb, high def audio, etc.
Anyway.. maybe not what you're looking for, but in a year or so maybe it would be a fit for your infrastructure.