First of, I'd like to congratulate the whole team for this project!
Now, I understand the Xna NetworkSession and related namespace and classes won't be developed anytime soon since there is plenty of things to do first on the core of ANX.
However, I've been myself looking into creating a framework for Xna which would provide its users with an abstract logic & network system and multiple implementations allowing them to code their game logic once and see it running seamlessly on Windows,
Xbox & WP7. You can have a look in the Indiefreaks Game Framework project hosted in codeplex at the following url:
While this framework is targeting SynapseGaming SunBurn Engine developers, this abstract logic & network system could be easily ported to Xna alone.
I don't have the time myself to help you implementing this side of things but it may interest you when you'll start looking into the networking side of things.
Hope it helps