Update: Blogger Buzz has something on this.
Today we’re bringing the embedded comment form out of Blogger in draft and making it easily available to everyone. This feature puts the comment form at the bottom of each post page, below the comments, instead of on the separate, Blogger-styled page.It would look even better if it actually existed! It's the HTML version of an ACORN voter.
The embedded comment form is more convenient for your readers because they can use it to post a comment immediately, without clicking over to a different page. It also looks better, since it matches your blog’s style and colors.
Update 2: Our Monastery of Miscellaneous Musings is broked. Our Cantor of Chemistry has the old style comments working. Our Camerlengo of Cars has the new style working. I guess the update is working it's way through the system?
Update 2: I just changed my blog settings so that you can leave a comment in a pop up window. That still works.