Looks like both Twitter and Facebook is busy with adding new features to their respective sites. Facebook is in the process of testing a new feature which will allow users to subscribe to a specific user and receive notifications whenever the user performs an action.
This feature is a bit different than the regular Facebook feed because it will send you a notification whenever someone performs an action just like Twitter shows you when a user tweets as you can see in the screenshot below.
The new “Subscribe To” feature will allow users to track certain users and find out what they are doing, however, considering the privacy problems that this feature would invoke among users, Facebook would have to tread carefully. Hopefully, Facebook will not allow the world to subscribe to your updates, or allow you to entirely turn off the feature.
Earlier last month, Facebook had rolled out a feature to allow users to control notifications on likes and comments, so this would just be another step forward.
(Source: All Facebook)