Read a pretty good post on The Evolution of Personal Publishing in Read/WriteWeb that suggests the Twitter and Tumblr were part of a natural evolution of Personal Publishing:

The image above is by Fred Wilson.
"…..The personal publishing market evolved from cumbersome web sites to online diaries called blogs to social networks and more recently to microblogs. Each form of personal publishing is different and each has its niche and audience. While social networks have been the most wide spread, the content creation there feels different from publishing. Because traditional blogging platforms are powerful and still require technical know-how, microblogging has evolved as an intermediate form of self-publishing. Microblogging has a shot of spreading blogging further into the mainstream as well as swaying some professional bloggers to start personal blogs.
It will be interesting to see what will to happen to microbogging in 2008. Do you think it is going to take off? Do you have a Tumblr blog today? Are you likely to get one soon? Do you use Twitter?"
I also just posted on Twitter Traffic.
