Except I don't like the way it works. The window it creates is too small, and it puts quotes around the text one is going to comment on. I'd rather it used <:blockquote> markup.
This version saves me some keystrokes. I wish I could get rid of the quotes though. If anyone knows how to do that, or where people post better "BlogThis" scripts, please let me know.
PS. This has to be all one line to put in a URL: