I managed to get the json to parse with jQuery 1.3 which is less strict than 1.4...
Thanks for this report; I believe that isPrivate relates to an internal privacy setting; if a network is private, then all objects will have that attribute set to true. It doesn't relate to the privacy settings for the object itself.
In terms of parsing, my understanding is that the json is wrapped with an extraneous (), so if you remove that, it should parse correctly in any tool.
Ah ok. Thanks for the reply Phil... Might you be able to help with a somewhat related request?