Hovercards enhance plain Gravatar images with information about a person: name, bio, pictures, their contact info, and other services.
Earlier this services is provide by only in WordPress.com users but it is now officially available for self hosted WordPress blog,through Jet Pack Plugin.
To see hovercards, look at any blog post on a blog which has enabled Gravatar Hovercards and has comments. If the commenter has a hovercard associated with their gravatar, mouse over their image and the hovercard will appear.You can see this feature on this blog.
How to Install Gravatar Hovercards in your blog ?
Go to your WordPress admin Panel >Plugin >Add new >Install and activate Jet Pack Plugin.Now you will be able to see Jetpack button under Dashboard section.Goto Jetpack setting and activate Gravatar Hovercards.
How to Customize Gravatar Hovercards ?
For Customizing your Gravatar Hovercards, Go to Gravatar.com and register there to add your avatar and bio,contact inf etc.You can also add your websites links and your Social networking site.
You can view my profile at Gravatar.com .