I think micro blog is a blog that only post short content. Twitter is one of the example, tumblr is another. You can make FB as micro blog too if you want
It's a type of blog that lets users publish short text updates. Bloggers can usually use a number of services for the updates including instant messaging, e-mail, or Twitter - these posts are called microposts, while the act of using these services to update your blog is called microblogging. Social networking sites, like Facebook, also use a microblogging feature in profiles - which is called "Status Updates".
Agree! I personally wouldn't say twitter is microblogging....twitter is only about status updates. But Tumblr is great....even better than the normal blog if I can say