Newspapergrl tells the story of a blog gone away at the hands of Wordpress. The moral of the story is that if you use another company to host your blog you're at their mercy. Everything you write could be gone someday without warning or explanation.
The only way to prevent this is to take matters into your own hands and run your own server. Of course, that too is subject to the whims of nature and man, but you stand a better chance of controlling your own destiny.
But what does this say of the blogging "revolution" if the only ones who really have a free voice are the ones who have the skills to run a server or pay to have someone run it for them?