I know that we have the ability to add custom fields to an individual post. I am wondering if there is a means (plugin/hack) to create a pre-defined post or page type. I've seen individual plugins (ex. GeoPress, ipodcatter) that add additional data to a post, but am talking about a common infrastructure that would result in a drop down selector at the top of the "Write" page that would let me select a specific type of post (ex. GeoPress, Travelouge, Podcast).
Once selected, I would then get whatever custom fields are included for that specific post/page type. For example, if it were a PodCast, I would see "Show Notes", URI (if external feed), Upload button (if posting the MP3 to server) and any other fields required to create a valid iTunes RSS feed.
Rather than building infinite variations on the same theme, it seems like WP needs a common infrastructure/manager for this functionality. Then devs can build against it in a consistent way. This allows even simpler UI and data elements.
In Xaraya, the plan was to make the posts table infinitely malleable by linking it to a dynamic data table that would hold all of the custom fields. As I recall, this proved problematic over time. I would suggest that all of the core post data remain consistent. Then devs of "post/page type" could be free to build DB tables for just their custom data and the core post/page type system would hook the two together for I/O.