So it turns out that if you need some code to read media information out of an m4a file the only viable option to be found on the interwebs is a project called Atomic Parsley. Written in C/C++, you can tell a lot of time was put into reverse engineering the structure of MPG-4 audio file meta data and specifically, the types of tags used by iTunes.
The downside to that set of code is that it is written as a command line utility (global state, lots of fprintf, and exit(1) for error handling) and not at all structured in a way to be easily used as a class or component; especially from managed code.
Since what I have been looking for is some code that can be used from C#, I took the pieces of Atomic Parsley that I needed and restructured them as C++ classes. From there it wasn't too hard to create a C++/CLI wrapper for easy consumption in C#.
On the nostalgia side: It has been a long time since I've seen calls to malloc and I even forgot for second that unmanaged memory needs to be manually initialized to NULL.
And on the new technology side: this was a good foray into the latest C++/Cli syntax, using VS.NET 2010 and .NET4. It's getting more and more like C# in flavor but is still feels cumbersome in comparison. That being said, when creating a shiny new managed interface around legacy code, it cannot be beat.
So if you are looking for a mechanism to read meta-data from iTunes/m4a files the result might be helpful. Check it out on google code.