Tried it out last night and it works beautifully. It fits into the networking thread of last in that I've decided that for communication i'm going to use Gzipped Base64 encoded XML. That gives me a nice compact format that's quite portable. Already tried out sending a such encoded message from a perl program on Linux to .NET on Windows and it worked beautifully. And it's 90% smaller than plain old XML.
Maybe if the Fast Infoset Project takes off, there'll be a more compact binary XML. In the meantime, this approach is at least easy for anyone to read, what with the ubiquity of gzip and b64.