Ning vs. DotNetNuke. and the difference is what?

Feel free to ignore me I'm just thinking out loud. So I'm reading TechCrunch about a 500 million dollar company called Ning. So what do they do?:

http://about.ning.com/product.php

Umm this is looking a lot like a DotNetNuke site to me...

I guess the difference is that they host the sites. Seems that there is nothing stopping any of us from using DNN to launch our own 500 million dollar company.

Oh but they have a bunch of really high-tech widgets...

anyway in un-related or perhaps related news I just checked into CodePlex the SilverlightDesktop.net code that allows for "instances". This was the last thing I needed before I could make the DotNetNuke version. I should be starting on that this weekend.

This allows a person to place a instance of SilverlightDesktop on the page and configure it to show just one SilverlightDesktop module. For example the email module.

Once all this comes together imagine the social network sites we could build...