Andrew Nacin has written an interesting article on the new Post Formats feature in WordPress 3.1
Andrew explains the point of the feature:
“With term names and such, we went through great lengths to ensure formats were as portable as possible. The idea behind the feature is this standardization and portability for a segment of bloggers. Many designers of themes used for microblogging wanted this ability to offer structured, well-defined content, beyond what could be done with categories and tags. It’s designed so when you switch to a different theme — a specific kind of theme, at that — your content doesn’t lose its most fundamental context.”
Much more at: http://andrewnacin.com/2011/01/27/on-standardized-post-formats/