If you click on the "more..." link, you will be taken to a site to choose the account you want to use:
I'm particularly pleased about the ability to support OpenID, something I've written about both here and over on Disruptive Telephony, although that's not particularly surprising given Six Apart's support for OpenID in the past.
There's a larger story to be written here about TypePad Connect and how it is part of the greater battle going on both with regard to your "identity" across blogs and also where your comments are stored. The Read/Write Web had a great article on the topic a year ago when TypePad Connect first came out. For me, since both this blog and DisTel are already hosted on TypePad, the issue about having your comments reside on TypePad's servers is irrelevant, really, since they already are. Another time, though, I'll write more on the larger story.
In the meantime, feel free to leave comments through being logged into those services (and saving yourself filling out the form).