Recently we had an idea to test one of sites being developed from multiple client locations - so have a distributed test.
Since I am usually oriented at Microsoft product and moreover I remember old Web Application Stress Tools from Microsoft thst was really good for that time, I believed there should be something for distribute testing in Visual Studio 2008 Team Suite Edition.
Sounds logically? Not for Microsoft!
VSTE does not support distributed testing.
If you really want it so much - you should install separate product: Visual Studio Team System 2008 Test Load Agent
Pricing? Well.. Around $5000 for volume license. No other options.
But! there is a 90-day Trial here: http://www.microsoft.com/downloads/details.aspx?FamilyID=572e1e71-ae6b-4f92-960d-544cabe62162&displaylang=en
Again but! It does not work for me - I have VS 2008 SP1 but trial is compiled against pre-SP1 libraries. Really there are LOTS of reasons it may not work for you at all. Some of them are here: http://weblogs.asp.net/okloeten/archive/2008/09/09/6612870.aspx.
So it seems we'll look for some other product - more friendly and worth its money...