I posted a few entries today using JustBlogIt, a Firefox extension, and so far it works very well. While reading posts in Bloglines I can righ-click on the post and select JustBlogIt! and it opens up a Movable Type editing window, similar to their QuickPost feature.
JustBlogIt populates the body with either the entire post or with just the text I have selected. It also grabs any trackback links if applicable.
Unlike the QuickPost feature in MT, JustBlogIt works with various newsreaders as well as when you want to blog from a page you are visiting.
So far it is working very well.