First of all, if you don’t know what OpenID is, go read about it. Now that you’ve been briefed, here’s something that might save you from a couple hours worth of googling: WordPress.com acts as an OpenID provider, meaning that you use your WP.com account to, for example, post comments on Blogger blogs that allow to authenticate for commenting with OpenID (most do, AFAIK). However, the reverse is not possible: if you have an OpenID that’s not from WP.com, you cannot use that to post authenticated comments on WP.com blogs. After a lot of googling I contacted their staff about this, and received this response:
> In short, I would like to allow people with external OpenID’s (e.g.
> Google’s blogger) to be able to comment on my wordpress.com blog using
> that external credential. I’ve search throughout the forums, but the
> few threads I found about this issue end up with a message telling to
> contact support directly, which is what I am now doing! So, is this
> feature planed, or not? Even if the latter turns out to be the case, I
> think it would nice to have some mention of it on the documentation,
> because being WordPress.com an OpenID provider, it is natural (IMHO)
> to expect it to be a consumer as well. In my case, this would have
> saved a couple of hours googling…
> That’s all. Thanks in advance (and congrats for an awesome service!)
We don’t currently offer the ability to use OpenID to post a comment to a WordPress.com site, and at this time don’t have plans to do so in the future.
I have entered your request as a suggestion, however, and we’ll keep it in mind as we continue to improve and upgrade our services on WordPress.com.