Most of the time I use the version of NUnit that happens to be installed on my system, and I only infrequently check for updates. When I visited the home NUnit site today I noticed that the final version 2.4 of NUnit has been released. You can download it here (release notes). It was released over a month ago and includes several enhancements such as a new syntax and internal architecture for Asserts based on the constraints found in JMock and NMock.