Blogger has been making 'improvements', and made a terrible mess of the comment feature. I was completely unaware of this until chigiy at The Gardeners Anonymous Blog wrote a post complaining about it.
I have changed the comment setting to 'registered users' It allows anyone with a Google/Blogger, AOL/AIM, LiveJournal, TypeKey, or WordPress account to leave a comment. There's also an OpenID option for blogs not hosted by any of the above. The downside to this 'feature' is that anonymous comments are not allowed. I'll be emailing blogger about this, but in the meantime, I'm going to add an e-mail me button so those of you without blogs can contact me.
EDIT: In playing around a little more, I discovered that the 'anyone' option has OpenID and allows anonymous comments. I guess I won't have to email blogger after all!