In reply to Ted Clayton.

Post Formats are, at their very essence, a taxonomy. (A taxonomy is just "a way to classify similar things".) As a taxonomy, post formats are analogous to categories and post tags. Unlike categories and post tags, which classify posts according to the content or topic of a post, post formats classify posts according to the type of information/data in the post: an image, a video, an audio file, etc. - regardless of the content or topic of the post.

But post formats are more than just a taxonomy. They have some extra fanciness built in to make them easier to use in creative ways by Theme developers, and easier to expose in the Theme. The main problems with post formats are two-fold, but related:

1) No consistent way to store meta data associated with a given post format
2) No consistent user interface for the user to enter meta data associated with a given post format

The changes to core originally slated for WordPress 3.6, but ripped out at the very last minute (during beta), were aimed at resolving those two issues. Until they are resolved, I don't think we'll see widespread user adoption of post formats, even as more and more Themes incorporate them into their design.