Jamie Cansdale, who develops TestDriven.NET, is adding a new test runner that uses MSBee. This means that for a C# or VB project, you'll be able to try building the project using MSBee as a test for .NET 1.1 compatibility.

You can read more about it, and sign up to be an early adopter, via his blog post: http://weblogs.asp.net/nunitaddin/archive/2006/03/01/439359.aspx