Virtual Server 2005 R2 SP1 provides a new option to allow you to control multiple simultaneous VMRC connections:

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Now, under Virtual Server 2005 R2 or earlier you could always have multiple people connected to the same virtual machine via VMRC at the same time.  The problem with this is that it is possible for someone to 'watch what you are doing' with no real indication that this is happening.  Virtual Server 2005 R2 SP1 disables this by default - and restricts you to having only one person connected to a given virtual machine via VMRC at a time.  You can change back to the old behavior by checking the option above (on the VMRC configuration page).

Cheers,
Ben