Exploring the msevents sites, I can across the following virtual labs, which I consolidated into a single list. I have not been through all of these yet, but plan to do so :).

What's New in Microsoft Windows SharePoint Services 3.0 Feature Walkthrough Virtual Lab

What's New in Microsoft Office SharePoint Server 2007 Feature Walkthrough Virtual Lab

Introducing Content Types for Windows SharePoint Services Virtual Lab

Creating Workflows for Windows SharePoint Services (TechNet) Virtual Lab

Microsoft Office SharePoint Server 2007 Enterprise Features Administration Virtual Lab

Microsoft Office SharePoint Server 2007 Records Management Deployment and Configuration Virtual Lab

Enterprise Search Overview (Lab 1 of 8) Virtual Lab

Forefront Security for SharePoint Virtual Lab

Getting Started with the Business Data Catalog in Microsoft Office SharePoint Server 2007

Publishing Exchange Server and SharePoint Server with ISA Server 2006 (Refresh) 

Synchronizing data between SharePoint 2007 and Groove 2007 Virtual Lab