What I think about this question is that PMBOK and Agile represent completely different approaches to project management.
The PMBOK takes a deterministic detailed approach to project management that can be used (at least parts of it) in _any_ project be it software (agile or not) or building construction.
Agile is a movement based on values and principles (not prescriptions of "best practices" like the PMBOK).
You can be an Agile project manager and look at the PMBOK for "things to consider when managing a project", however, if you are looking for a prescription on how to do Agile project management you are (IMHO) looking for the impossible.
Agile does not prescribe what you must do, just what values and what principles you should look to for guidance, the rest is up to you.
This is probably one of the factors that makes Agile adoption so hard. People think they can just do stand-ups, retrospectives, TDD and everything else will work. That's not how it goes... those are only practices, what you should focus on are Agile values and principles: www.agilemanifesto.org.