You can start a micro blogging community just like twitter ™ with these Free Open Source Microblogging script, and also you can try these microblogging applications.
Free Open Source Microblogging script
1.StatusNet is the open source micro messaging platform that helps you share and connect in real-time within your own domain.
With StatusNet you can encourage collaboration, build and engage your community, and be in command of your brand. Previously Laconica is the engine which runs the popular micro blogging site Identi.ca
It is built with PHP/MySQL & offers a smooth usage as it is a widely used, mature application.
2.Yonkly is build on Asp.net MVC framework is another Free Open Source Twitter Clone and Microblogging script as well as Web service.
Based on ASP.net MVC framework makes it really fast
Very Easy to setup and take very less time
Besides the open source version, it has a hosted & an advanced standalone version.
3.Jaiku was the microblogging site of Google. However, they decided no longer to develop the code but make it open source under the name JaikuEngine.
Anyone can set up and run their own JaikuEngine instance on Google App Engine. Alo, there is an open source mobile client & frontend.
4.Floopo this free microblogging script is built with PHP & MySQL.
It functions very similar to Twitter & provides a powerful backend to manage the whole system.
5.Sharetronix Opensource – The Ideal Microblogging Tool for Your Community
Sharetronix Opensource is a multimedia microblogging platform. It helps people in a community, company, or group to exchange short messages over the Web.
Microblogging application
6.Jisko is a PHP microblogging application that offers a Twitter-like API for developing it further.
Users can have their profile pages, message with each other easily & Jisko is compatible with mobile devices.
7.PageCookery is a single-user microblog which can pull data from social networks like Flickr, last.fm, etc.
It offers an Ajaxed interface where users can comment to the entries easily.
P.S. The original page is Chinese. However, you can view the English version behind Google Translate.
8.EchoWaves is a ready-to-use hosted application where the source code is offered for free.
It is a collaboration tool & a social network which is focused to conversations rather than the users.
9.P2 WordPress Theme This is a WordPress theme which can convert your blogging engine into a Twitter-like interface.
It has real-time updates where new posts & comments come in without reloading. There are also inline comments, posting from homepage & more.
10.TypePad Motion enables publishers and marketers to create vibrant, branded communities that deepen loyalty and increase page views while giving you total control of your brand.
It is based on Pownce & MovableType Motion and built with Django.
P.S. You can choose Hostgator as your microblogging web hosting, because they suport 99.9% Uptime, cPanel, Unlimited Space and Traffic, $9.95/m.
WordPress is the world’s most popular blogging platform, used by a staggering 202 million websites. As simple or as complex as you want it to be, WordPress is supported by a wide array of plugins which can be used to transform a standard blog into anything you could possibly desire. Besides blogs, WordPress can be used as a straightforward content management system to power anything from an e-commerce site to a social network. 
