You can create a formatted version of a messenger conversation for internal use or creating a public facing blog.
If it is a public facing blog, then it is important that it can be indexed by search engines (like Google). Search engines work through the content (HTML formatted) and the links contained with in the content to crawl the blog.
The following getting started guide steps through how a developer can set it up a blog that is suitable for indexing.
The user experience (adding comments etc) can then by progressively added using jQuery/js and the onemand MESSAGING_CONVERSATION methods.