Project Description from the project home page on CodePlex:
"This tool takes a WCF trace file and a WCF client proxy, or a WCF interface contract, and generates a unit test that replays the same sequence of calls found in the trace file. The code generated is easily modifiable so that data variation can be introduced for the purpose of doing performance testing."
Rob Jarratt showed us a demo for the latest version of the tool last week. If you have created any type of test (unit, load, manual, etc) in Visual Studio, then you are already familiar with how the WCF Load Test works. When you install the setup package, the tool adds a new project item type to Visual Studio called "WCF Test" and the test code generated by the wizard will be added to the new test item.
Something that I really like about this tool is that it generates the code for populating the object model (based on your data contracts), which will be then converted into a WCF message that matches the original trace when the tool uses the generated proxy or the channel factory. The object model is very easy to work with and you don't have to mess around with the underlying XML. The code generation for the object model is very flexible and supports nested properties and collections. This is done by looking at the captured message and reflecting over the data contract types you provide as input.
Another cool feature is to allow you to generate one test class that generates all of the messages captured in the trace, or generate one test for every single message. This gives you higher flexibility when you want to apply various load patterns and test mix models to your load tests in VSTS 2008 Test Edition or Team Suite (and by the way, the tool supports Visual Studio 2005 too).