Just as a quick reminder: Vienna, NetNewsWire and probably a few other apps implement Brent Simmon's excellent and useful External Weblog Editor Interface. If you implement the receiving portion of this protocol, we can send you information about posts, websites, etc. which you can then re-use in your application.

Vienna even has a facility for creating plugins (with toolbar buttons and menu entries) that make this process a one-click affair for your users. If you have any questions about this, don't hesitate to ask on the Developer Forum. Applications that already implement this include Cocoalicious, Pukka, Ecto, MarsEdit, etc...