Because I finally decided that I would rather switch than fight, I finally switched this to the new Blogger Beta. As you can see, some of the Contributors are gone. That's because Google, which owns Blogger, is now forcing people to sign in with their Google account. Contributors will come back, supposedly, as they sign in with Google accounts.
If you can't sign in to post or comment, or are just confused, try going here and signing in with your Google account (a Gmail account is actually a Google account, so that works). If you don't have one, the page should prompt you to create one.
If you just don't want to get a Google account for whatever reason, you can still log in, for now, using your old Blogger account by going here. I think this will also prompt you to convert to a Google account on your way. You should do it -- maybe. Give it the old once over.
I'm sorry for the hassle. I put this off as long as possible so that the first wave of bugs would be worked out before switching this blog. Progress -- it eventually swallows us all.