Earlier this year I wrote my two step guide to Linear Workflow. Since then I have received a lot of email about it. It's a tricky one to explain in simple terms. I did my best to narrow down my description to cover the basic concepts. Some people got it. But I can tell from the email, that others saw gap's that I did not adequately fill.
Luckily for all of us. Fredrik Averpil has written an excellent article on Linear Workflow in Maya 2010 with pictures and diagrams and examples of how this also applies to compositing in Nuke 6. You can check it out here.