WordPress announced the new notifications in a blog post, suggesting they act as the “pulse” to your “living and breathing” blog.
“Whenever another WordPress.com user follows your blog, or likes one of your posts, Notifications will tell you who your newest fans are by adding a new note to the stack.
If you’re a fan of Google+, as we are, a lot of this will be familiar as many parts were inspired by Google’s toolbar, and a bit by Facebook’s new real-time stream.”