Rob Eberhardt

It's possible after all.  XP Pro's Remote Desktop can be hacked to give concurrent sessions.

To explain:  Windows XP's Remote Desktop rocks, as does its ability to give me my console session later (with my work uninterrupted) from another machine.  Glaring in its absence, though, is the ability to remotely-rock while someone is locally-rocking the machine.  This can stink in a big way. 

For example, too often I've remotely logged in for something quick, only to see this nuisance:

Rather inconvenient.  Even worse, though, I've often been logged in and working remotely, when someone locally logs in.  No warnings or explanations, just *bam* disconnected!  (At least the first situation confirms the handover with both people.)

For history:  Remote Desktop's daddy was Windows 2000 Server's Terminal Services in Remote Administration Mode, which did allow (limited) concurrent sessions.  Microsoft added the console-session flexibility to XP's Remote Desktop, but dropped the concurrent sessions.  Then 2003 Server's (renamed) Remote Administration wrapped in XP's console flexibility.  Later, XP's SP1 promised concurrent access, then SP2 did.  Two strikes.  It did make an SP2 beta though, before being yanked later...

The silver lining:  Thanks to the termsrv.dll from that SP2 beta, it's possible to hack XP for concurrent Remote Desktop sessions in a few minutes.  Just change a registry setting, reboot to Safe Mode, replace the DLL, and boot back into homebrewed XP Remote Administration goodness.

For the do-it-yourselfers:  Don't wait for Longhorn (or whenever-they-may-get-to-it): here's the how-to article, and here's the needed termsrv.dll file.

Update:
I just stumbled on sala source's Terminal Server Patch, which wraps up the whole process in a single convenient patch.  Very cool.