From Wikipedia: Microblogging is a broadcast medium in the form of blogging. A microblog differs from a traditional blog in that its content is typically smaller in both actual and aggregate file size. Microblogs "allow users to exchange small elements of content such as short sentences, individual images, or video links".
As with traditional blogging, microbloggers post about topics ranging from the simple, such as "what I'm doing right now," to the thematic, such as "sports cars." Commercial microblogs also exist, to promote websites, services and/or products, and to promote collaboration within an organization.
My favorite micro blog other than Twitter is Tumblr. I only follow 100 or so people right now and my dashboard is constantly filled with beautiful pictures, smart text, and funny videos at all hours of the day. Writing can be a lesson in lonely, and I think that micro blogs like Twitter and Tumblr have given the writer a way to take a break and come out and play without ever really leaving the writing cave.
Micro blogging is there to help you reach your fan base or build one. To inspire you when your muse is on vacation and to give you a social outlet while you work. It is vastly better than being punch drunk Hemmingway. Tumblr is a free service like blogger but cooler. It has many cheap themes or free themes you can easily install with the click of a button. You can reblog friends, and your fans can reblog stuff about your book and it becomes this huge news outlet and your fans can ask you questions that you can answer publicly and that can then ... be reblogged.
Try to remember to schedule your Twitter/Tumblr time or you will never get anything written. Other than that have fun reblogging!