Facebook is in the process of testing a new feature which lets you subscribe to all the actions of a specific user. In other words, you can receive notifications anytime a specific user takes an action on Facebook. It also appears to be Facebook’s answer to Twitter’s follow feature. As a Facebook user who has seen the feature explained to us, “By subscribing you don’t miss any updates from people you subscribe to.”
This means you can “Subscribe” and be notified about a persons every move on Facebook – not just see their status update in your feed, but be alerted in your notification area that they’ve made one! This area is normally reserved for updates directly related to something you have commented on or liked, whether it’s a comment, post of photo. This bings up huge “stalker” issues, and I’m sure Facebook will face more outcry when this starts to be seen in regular profiles.
Source: All Facebook