The patterns and practices team, led by J.D. Meier and including Larry Brader and Carlos Farre, has teamed with a bunch of expert load testers as well as industry expert Scott Barber, to create best practices guidance for load testing. The guidance is hosted on codeplex at http://www.codeplex.com/PerfTesting.
I had a great meeting with JD last week when I was in Redmond last week. I love the way he thinks, looking for underlying patterns in things that are timeless and independent of other factors (like type of target app and tooling to drive the tests). One of the goals of the performance testing guidance is to distill out this timeless information into nuggets that will stand the test of time. Then tie that together with additional guidance on things like tooling and target apps (these things that are more temporal), and to give guidance on how to put the perf testing into practice with a given toolset against a given target app.