How plurk work for you? I didn't use it before. I use 2 micro blogging sites twitter (no-follow link) and indentica (Do-follow link). Right now I try another one, Jaiku.
Plurk is a very good social media site you can use to keep in touch with friends, dont know how effective it is though if used in internet marketing. Plus I don't like the timeline idea, also the messages... they look like thin strips of post-its.