Over at systmecenterforum.org I found a post stating that SCE2007 licensing will count a Virtual Server as a Server.

I wanted to clarify an issue related to SCE 2007 licensing. Unlike Operations Manager 2007, agent-managed virtual servers in Essentials 2007 actualy DO count against the 30 server total. This is because SCE actually considers OS instances, rather than devices as in MOM 2005 and Ops Mgr 2007.

Read more at http://systemcenterforum.org/essentials-2007-licensing-and-virtual-servers/