User Interface Engineering posted a great, short interview with Rolf Molich who has conducted a series of studies on the effectiveness of usability techniques (CUE-1 through CUE-4).
My favorite paragraph from the interview, which I wholeheartedly agree with:
Usability tests are spectacular. They are excellent for convincing skeptical colleagues that serious usability problems exist in an interface. But they are also inefficient and costly. We should use them mainly in an intermediate phase to establish trust with our colleagues, and then use much more cost-efficient preventive methods such as usable interface building blocks, reviews based on standards and proven guidelines, and contextual inquiry.
