Learning Movable Type: TypeKey Authentication for Comments. I thought I was done, but it turns out there is a ton of work to be done. MT 2.661 blogs are *not* automatically converted to MT3.0. There is a boatload of work to do as covered in Elise.com and also in "Anzi":http://www.anzidesign.com/archives/000443.html
You can see this because right now my comments are pretty broken across all the sites. Sorry, I'll try to fix this week.