After two weeks of testing, finally OpenID commenting has been released officially for Bloggers around the world. You can check it on Settings > Comments. You will have four options there:
* Anyone - includes Anonymous Users
* Registered Users - includes OpenID
* Users with Google Accounts
* Only members of this blog
For convenience, you can set to Anyone, with some risk that anonymous poster will be allowed to post. If you want to identify all commenter, you should use second or third options. Fourth options is the most strict options by only allowing member of the blog (if you have several contributors) to comment on the blog you are running.