UPDATE: NOW JETPACK BY WORDPRESS.COM PLUGIN ALREADY PROVIDES YOU OFFICIAL WORDPRESS.COM LIKES MODULE SO THERE IS NO NEED OF USING THIS PLUGIN.
You might have noticed a content like feature at the bottom of most WordPress.com’s blog posts. There is a “Like” button, which when clicked, displays a Gravatar image of the bloggers who liked that post. JetPack by WordPress doesn’t provide you with this feature but still you can have it for your self hosted WordPress blog.
Now there is a plugin Gravatar Like in WordPress.org repository that simply adds a like button after all of your blog posts and pages. All you need to install and activate it.
This plugin is available in WordPress since 2011, it works fine, it adds same type of like button as of WordPress.Com but still bloggers are searching for it everywhere on Internet, its not yet famous. I searched for WordPress.Com Like Button for WordPres.Org but it never came on the top results then I started reading about all kinds of ‘Like Post’ plugins in WordPress.org and suddenly I came to know about this plugin. I clicked Gravatar Like (title) of this plugin thinking ot it some kind of plugin that adds a Gravatar type of functionality in WordPress but I came to know that this is the unfamous plugin all bloggers are looking for.
Many are discussing about WordPress.Com like button on Internet and waiting may be on the next JetPack update; automattic would be introducing like button for self hosted blogs. But now no need to wait, this plugin will be satisfying your demands. If you use it after JetPack‘s sharing feature, it will be giving same look as you see in other WordPress.com blogs.
Whenever anybody likes a post, two core things happen. one is blog author sees the “like” and he can click-through the Gravatar profile and two is clicking “like” saves the post in your homepage dashboard of (WordPress.Com)