Starting today you’ll notice a new feature at the bottom of all WordPress.com blog posts. WordPress has enabled a “Like” button. When clicked, it shows a Gravatar image for all the bloggers who like a post.
When you “like” a post two core things happen. First, the blog post’s author sees your “like” and can click-through to your Gravatar profile. Second, clicking “like” saves the post in your homepage dashboard (in the “Posts I Like” section), so you can share it with others, or just keep it around for future reference.
Read thee full article about this new feature at Like a Post? Well Then, “Like” It! — Blog — WordPress.com.