There is an interesting post over on the MindJet blog - Blog Better with MindManager.
The article first provides some thoughts as to why you should plan your content. After that the author - Tim Leberecht - walks you through using mind manager to map out your post.
Start with a central topic, gather research into the map, make connections, build the outline, populate the full text using the notes feature then copy and paste into your blog client interface. Tidy up and post.
This is a great post from Tim, and it applies to more than just blogging. This is a fantastic roadmap for planning a document you need to write using Mind Manager.