From the project page:
"At long last, NUnit 2.1 is released in its initial Beta version. Highlights of this release include support for the .NET framework 1.1, the ability to run test suites across multiple assemblies, improvements to the GUI interface, new command line switches for both GUI and Console runners, some degree of integration with Visual Studio and new TestFixtureSetup and TestFixtureTeardown attributes.
With so many changes, we expect to need several Beta releases and want to receive your feedback as quickly as possible. Download the new install package and let us know what you think."
[Via LarkWare News]