I gave a talk on Mozilla Software testing approach as part of my Software Testing course. You can find the slides (built using S5) here. I introduced a number of tools that we use for automated and manual testing, and also gave an overview on parts of the process employed to use the tests in real life.
You can grab the slides. I hope that they'll be useful to you.
Update: I made a mistake when writing this post, which caused the links not work. I've fixed that, so now you can really see the slides. 
Update 2: I uploaded the presentation to the Mozilla Library, which is a collection of Mozilla-related presentations. Thanks to Clint for pointing this out!