Hyper-V is getting more exposure now that SharePoint 2010 is nearing it's launch as only x64 platforms will be supported. Previously in MOSS/WSS 3.0 developers can use Virtual PC or XP Mode to virtualize their SharePoint server.
Hyper-V provides greater network functionality than Virtual PC, allowing you to create Virtual Internal and External network adapters via the Virtual Network Manager. It's also possible to add Legacy Network Adapter.
Often you need internet access as well as access to your internal resources such as AD. I found this to be the case when installing the SharePoint 2010 Beta / SharePoint foundation Prerequisite bits
The following were components of SharePoint 2010 Pre-Requisites that tried to connect to the internet in my Hyper-V SharePoint 2010 client:
Microsoft Geneva Framework Runtime
Microsoft Chart Controls for Microsoft .NET Framework 3.5
Microsoft Filter Pack 2.0
Microsoft SQL Server 2008 Analysis Services ADOMD.NET
SharePoint and Hyper-V