+2  A: 

I use System.Web.Script.Serialization.JavaScriptSerializer

Bob
A: 

I've been using Json.Net. (http://james.newtonking.com/pages/json-net.aspx) to serialize.

mheckmann
+1  A: 

Here you can find a very well-written open-source solution for parsing JSON data:
http://techblog.procurios.nl/k/618/news/view/14605/14863/How-do-I-write-my-own-parser-for-JSON.html

It is not native, but I have used it recently and did the job...

Dyer