You would be surprised. This topic came up for tumblr users and I remember reading that quite a few of them would pay for premium features. They each all have

You would be surprised. This topic came up for tumblr users and I remember reading that quite a few of them would pay for premium features. They each all have their own business model, Tumblr I think is still tweaking theirs but they currently offer paid themes. Tumblr users are incredibly supportive of Tumblr. Same goes for WP, and I'm sure Posterous. You will have the casual 'free' users, and you'll have the users who will actually shell out a significant amount to support their blogging medium.