We’ve seen this through the media – if a company or individual says that they have a Twitter account, people (typically) know where to find it. Compare that to a blog, and there might be so many similar blogs that it becomes a challenge to find the right one. (there may only be a few accounts that resemble the person, although they aren’t updated).

Should Twitter branch out to be more like Tumblr in the regard to being able to post more forms of content other than text and links, I would then consider the people who use it to be bloggers. But again, they would also have to remove the “140 characters” limit and this likely won’t happen.