"This isn't VNC-like screen sharing where when you take control of an existing PC desktop. Logging into RDC gives you a full virtual desktop on the PC... if someone was sitting at the PC when you fired up RDC, they'd have no clue you were mucking around. Slick, but unnecessary as my PC will now headless, keyboardless, and mouseless... sitting in a dark corner of my office... under a blanket."

In other words, what can be done with a headless X server hooked to a VNC server/client. (NB: I thought RDC sounded reasonable as well, until I realized this was Microsoft's way of saying 'If you want background login, we're going to make you use our proprietarish, license-fee-chargeable protocol instead of VNC.' See minor expected Slashdot furor back whenever XP was still 'new.')

I'd expect outright emulation to be pretty reasonable these days in all the ways it wasn't times past (how many PC applications require 'custom' or in any way 'fiddly' hardware anymore?), but these days you're already trading in cycles to have Quartz or whatever the Longhorn display layer is, so it's probably not worth the overhead or costs for commercialware if you actually own hardware and can pay your electric bill.

When it comes to sane remote-access protocol design, I keep peering back at http://nomachine.com/ . But I've never had a chance or reason to use their stuff. The interesting thing about their crap is that they offer RDP and VNC to NX bridgeware... so presumably a sort of sanctioned-or-at-least-actively-developed, relatively performant way to get RDP on *NIX versus, uh, http://www.rdesktop.org/ . (I expect they've built off the rdesktop codebase, but it seems like doing the conversion to their NX crap on or near the RDP host might help mask some of the latency/crappiness issues.)