I have to admit that I had the same impressions of Ning that Nat Torkington did, and I don't even read TechCrunch. However, his writeup of a meeting with the Ning crew does a hell of a job selling the product. First off he explains how out of the box Ning isn't for me the "serious" hacker, but for communities of non-professional programmers, enabling a gentle slope for those who desire a Web application but don't have the obvious chops or connections. Second, the underlying Ning services seem eminently exploitable by a pro developer looking to outsource stuff like authentication and semi-structured data storage.
Like I said, I've been known to be wrong.