Ars tackles processor pipelining
Ars Technica has published a Technical Blackpaper on processor pipelining that'll guide you through the basics.
In the present series of articles, I want to devote some serious time to explaining pipelining, its effect on microprocessor performance, and its potential downsides. I'll take you through a basic introduction to the concept of pipelining, and then I'll explain what's required to make pipelining successful and what pitfalls face deeply pipelined designs like Prescott. By the end of the article, you should have a clear grasp on exactly how pipeline depth is related to microprocessor performance on different types of code.
Jon "Hannibal" Stokes even throws in a car analogy, although perhaps a sign of the times, it's really an SUV analogy. If you haven't wrapped your head around processor pipelines, this introductory article will PYAITK.