Ning launched! Lots of folks have a lot to say about Ning if you haven't bumped across it yet, but I'll say my bit about what is most exciting technically to me =)
Ning is a public, schemafied, taggable, and free datastore for the web. The public content stuff is the exciting part -- any app can query across any app other app's data. You can fetch, say, every entity in the content repository which calls itself a Dog. You can only modify what you own, but you can see anyone elses. Oh, you can fetch them programmatically in Ning, or as an RSS feed, or via custom REST services, or... well, be imaginative. This is pretty cool. It is one of those things that if you think about for fifteen minutes you can come up with some really cool ideas, but... but... the best ideas are far over the horizon. This is enabling more than anything. Stuff no one has ever thought of will appear.
It's standards based, its open, you own everything you contribute (but license it under creative-commons attribution based licensing by default) -- both data and code. Cool stuff.
Oh, and I am totally into situated software, but that isn't a technical cool point, so will talk about that later =)
I could go on for a bit, I'm pretty excited by this. Of course, I am also moving to Palo Alto next week to work there, so I had better be!
Major kudos to the 24HL folks who have been working like crazy to get this out, I can't wait to join you.