A dirty little secret about social sites is that sometimes it's the big media franchises that put them on the map. Often they drive adoption by a more mainstream audience once they start to dabble. This starts small at first but it can grow quickly.
This week Mediabistro launched a reader-powered blog using Posterous...
Via This is your blog. - TK
"This will be the destination for our community-powered blog. Here you'll be able to submit original work, such as traditional text posts, and multimedia such as videos, photos, and more. It can be educational, it can be artistic, and it can be anything that you think will benefit your media brethren."
As more journalists begin to dabble with Tumblr and Posterous. I suspect we'll see a lot more innovation. The attractivess of Posterous here in particular is its hub and spoke lifestreaming approach that makes it a solid launching pad for a brand's entire portfolio of socially connected content.