Hendy commented that Ning isn't open source.
Agreed. I'd like to see an Open Source online web-app development / code-generation / code-management / code-sharing platform. Possibly Trac could evolve in this direction (from a very different starting point.)
I notice that I missed something from the list of improvents (in that previous post I linked) in web development. I said templating-oriented development (eg. PHP), and object publishing systems (eg. Zope) were the only real changes from trying to program web-apps as though they were any other kind of app.
Perhaps I need to add continuations based servers like Seaside. I finally watched these videos and got how cool this is.
Essentially you're allowing the language to hide all the session / interaction management.