This graph does a good job of capturing the various metrics of internal communications.  I think it should include traditional (non-technological) Protocols like Face to Face.  I think it would also be useful to include specific "applications" of the merge between Styles and Protocols, i.e.:

Brainstorming + Web = Yammer/Twitter

Document Sharing + Web = Knowledgebase

Private + Email = Email

Then you can start to see crossovers, like:

Private + Document Sharing + Web = Knowledgebase

I also see a need for a metric that expresses whether something is structured/unstructured, formalized/unformalized, self-organizational/top-down.

For instance, on the Reality protocol, you can have informal brainstorming one-on-one face to face (water cooler talk or someone drops by).  Or you can have formalized (structured) brainstorming face to face (a scheduled meeting).

You can have a spontaneous discussion start up in Yammer (this) which is self-organized, informal brainstorming unthreaded over the web that changed to Threaded self-organized informal brainstorming over the web. :)

I think maybe one of the struggles for people is the ability or preference to access all these channels.  I may prefer email and Twitter and IM.  Other people like to drop by my desk and ask me questions. Others like to write blog posts and get feedback in comments.  I may be interested in that blog post, but because of all these channels, I'll probably miss it.

Another struggle is what we're talking about here... how do we bridge the channels?

And then Time is another biggie.  It's a nice idea to get everyone's input, or every interested person's input .. but not everyone is able to focus on everything at once.  There are weeks I'm so slammed I can't even read The Buzz.  Other weeks are slow, and I want to catch up on certain Hub threads or Yammer topics, but the party is already over.

The answer to these issues is where the magic lies. :)