In particular He lists "Five Steps to Accomplish Any Task"
Once you read the descriptions they bear an uncanny resembelance to the hierachy of requiremnts types defined in BABOK. (Business -> User -> Functional).
But so what?
Well, he has some great advice that when you've got no clarity on why you're doing something you should go up the stack, but when you can't get somethign started or finished you need to go down the stack. This is great advice for BAs.
Don't be constrainted by the exact stage of the project you're in - you should always be prepared to switch contexts to respond to the environment.
When there's confusion about what to do, you go down the stack, when there's confusion as to "why" to do something, go up.
P.S. http://www.minezone.org/wiki/MVance/GettingThingsDone has an amazing notes page on GTD. Great summary of the basic poitns.