I believe OpenID in its present form is unsuitable for mass usage the reason being that providing an intimidating blank textbox asking for your OpenID is perplexing for most users. A couple of articles about why OpenID is failing.
So whats the solution?
One good if not great solution is provide the user with a number of third party accounts he/she can login with. For example, a regular non-tech savvy user may not know that Google also provides OpenID support and even if a tech-savvy user knows about it, the URL is simply too long to remember. A good example of this usage is the login system at StackOverflow.
The plugin allows the user to provide his/her details via all the famous OpenID service providers (Google, Yahoo etc.) while commenting. A working example of the plugin can be found on this site itself (scroll down to comments).
To make this plugin work make sure you have OpenID for WordPress Plugin installed.
Here are a couple of instructions to make this work:
1. Download the plugin file
2. Extract the archive contents to the wp-content/plugins folder i.e. wp-content/plugins/third-party-accounts-login
3. Login to WordPress Administration Center
4. Activate the plugin
5. Goto Settings -> Third Party Accounts Login and set your preferences. Currently, you can choose from three different views- Only text, small icons, X highlighted (large icons) + remaining small icons. You can hide the icons you do not want to display by double-clicking on them and drag them to order them.
6. Add the following line in your comments.php page: <?php third_party_accounts_login(); ?>
7. Make sure that OpenID textbox is present in your comments page with an id=”openid_identifier”
A sample code:
<label >Please select one of these third-party accounts:</label><br/> <?php third_party_accounts_login(); ?> <br/> <label>Or enter your OpenId URL:</label><br/> <input type="text" name="openid_identifier" id="openid_identifier" class="textfield" tabindex="4" style="width:300px" />
Do let me know your suggestions or any other OpenID service providers you would like to add. One feature I will add soon is Facebook OpenID integration similar to RPXNow.