I backed Manton Reece's Kickstarter project for micro.blog back in January. Invites started rolling out this week and I got mine the other day. If you're interested, I'm setup at http://jsorge.micro.blog.
I'm not sure how I'll use this vs using Twitter but I do have cross-posting setup so my posts become tweets. I'm also thinking about writing a lightweight posting client for the Mac. but we will see.