Fred of ~Fragments fame posted this question from a friend who now publishes a periodic newsletter.
Newsletters, whether electronic or not are "push" type publishing. I have done email newsletters in the past and I stopped when I realized it is kind of a mini-spam. People may not complain because they are friends, but it is an enforced communication.
Weblogs, in contrast are "pull" type publishing. You post an essay and it is read by those who actually want to read it, WHEN they want to read it. Furthermore, your essay, once posted, will be available forever, or until your hosting company goes out of business, which will probably occur sooner. Your essay becomes part of the permanent references on the internet. You could become famous in your own lifetime... :)
I can send an essay to a hundred of my long-suffering friends or I can post an essay on my weblog and it can be read by thousands of people in a few short months. It will show up on Google for years if the topic is of sufficient interest.
I wrote an essay on shanty towns and I got hundreds of hits from students in England who were studying the social aspects of shanty towns.
The effort to post an essay on Typepad, complete with links to hundreds of supporting documents and images, is the same as for writing an email. There is no extra time involved. If you can handle email, you can be a published author on Typepad or any of the other weblog hosting companies.
In short, if what you have to say is important to more than five people and it is not proprietary, you owe it to yourself to have a weblog.
Try it. You may like it.
You can also become an agent for social change.
Marie has now been linked with a trackback. (See comments.) This is something else you cannot do with a push type publication. Web logs allow for continued linking and relinking of existing documents.
...If this post gets any more convoluted, it will look like a DNA chain.