Much kudos to Noctavis of Myther.com for sending in this:

If you go to www.cdmag.com you can catch a cool first look article (http://www.cdmag.com/articles/021/126/halo_preview.html) about Halo. It makes some interesting comparisons to certain, genre-stretching pieces of PC software, and anticipates that it may well go beyond them.

Among the cool things in this article are some hints about how communication will be implemented... hand signals, and possibly (if it works out) voice communication.