JSON will be a core type in PostgreSQL 9.2
This is nice, but it's a shame that after going to the trouble of writing a JSON parser in C and incorporating it into the main Postgres codebase, they didn't go one step further and add a json_project_key function that pulls values out of a JSON blob.  That, combined with functional indices, allows you to store JSON blobs in your database and index on values inside them, or put another way, get the data model benefits of a NoSQL database [1] without sacrificing the mature Postgres internals.The Heroku Postgres guys have been playing with this idea [2] using the PL/V8 plugin, which embeds Javascript as a supported language inside Postgres (and thus makes it trivial to implement the json_project_key function), but if Postgres is going to natively support JSON parsing then it shouldn't take an addon module to achieve this.[1] Attempting to forestall the thread-jacking: I know NoSQL databases have other benefits besides their data model, but for some applications that's certainly one of the benefits.
[2] https://gist.github.com/1150804