Do you think starting a Twitter-like microblog is a viable project ? Depending on the topic, there will be some adjustments in the backend. But I think with everyone going for blogs and forums, microblogs are very much forgotten.
You can talk about a topic and the same way, people can ask questions about it. If you do it properly, Google will pick it up like forums and blogs and bring traffic.
I do not know any micro blogs other than Weibo and Twitter. Perhaps it is time that we think beyond standard projects.