Sure, JSON seems to have lots of uses.

I know a few people who've been working on a JSON Schema for the more formal datasets. I worked on an Internet Draft for this for a while, before the effort crumbled. Like most of the Web though, JSON really tends to shine when it is semi-structured — with any additional structure applied to it, post-hoc, by the consumer. CouchDB is a good example of a system that embraces this property.