MSDN Virtual Labs are a series of guided, hands-on labs which can be completed in under an hour. You can begin accessing the Visual Studio Hosted Experience immediately with no installation required.
It's like working in a Virtual PC (or Remote Desktop) that has been prepared for you. For the moment there's only one Virtual Lab (Click Once Deployment) available for Visual Studio 2005, but more labs will certainly follow! A lot of labs are already provided for other "technologies" : Microsoft Office, SQL Server 2005, Visual Studio .NET 2003, Visual C#, Visual SourceSafe, ASP.NET, Smart Clients, Web Services, BizTalk, ...
Registering for a free account is quite annoying for non-US residents: I was required to fill in an US-State and the phone-number must follow a specific format for US phone-numbers ... Not so good!
Another note : the lab for Visual Studio 2005 has still to be performed with beta 1 of Visual Studio 2005. I hope they will quickly provide Virtual Labs for beta 2!
Update : Raf pointed me to another interesting link (Microsoft E-Learning) for those who want to play with Visual Studio 2005 : Get ready for Visual Studio 2005 with free E-Learning course and clinics. Microsoft E-Learning for Visual Studio 2005 is free until November 8, 2005.