Several months ago I wrote about switching from explicit to implict post types for my blog, and looked a little at generating an ActivityStream from content objects (posts) based on their properties. My thoughts have progressed on both of these things since then, and I've also added a few more post types to my site. Yesterday Tantek published a working draft of a post type discovery algorithm so to add to the discussion, here is the version of this that I currently implement; similar but different. I mostly use this to display different icons by posts.