James Clark, Technical Lead of the XML working group and author of expat recently wrote an interesting post about XML, JSON, and web development titled "XML vs the Web":
This isn't JSON triumphalism; Clark has well expressed mixed feelings about the turn.
If our pre-WhereCamp5280 meetup is indicative of how cutting edge developers are evaluating and selecting technology, JSON is definitely the future of sending features to geospatial apps running in the desktop, laptop, or mobile browser. But there's more to the web than browsers. I get a little concerned sometimes that going all in for JSON and HTML5 tech like WebSockets takes us even further off the web as integration platform than we were with GML and W*S.