So I was trying to configure Word 2007's blogging feature to post to my blog at GeeksWithBlogs, I noticed that it does so through a standard web server API called MetaBlogAPI, and it's pretty widely supported. I had no idea this existed (granted I may be out of the loop). It contains all of the functionality to add posts, view posts, and do everything blog related. Very handy.
Check out my blogs API (granted you can't do much without my account credentials!): http://geekswithblogs.net/mcassell/services/metablogapi.aspx