Facebook is reportedly testing a new feature which lets users follow a friend's every move.
According to the All Facebook blog, a new button, 'Subscribe to X' is appearing on a small number of users' screens above 'Send X a message' and 'Chat with X'.
Facebook has confirmed that it is testing the feature with a small number of users.
Clicking the button means that the user will automatically receive notifications whenever the object of their interest updates their status or posts new content.
The button is in principle similar to Twitter's Follow feature. One big motivation for Facebook to include the feature is to counter the way that Twitter has become the tool of choice for following the daily activities of celebrities.
And if users could be persuaded to 'subscribe' to businesses, it could do wonders for the company's ad targeting, and therefore revenues.
However, if the feature ever makes it out of the test stage and into the real world, it's likely to cause rather more controversy than Twitter, coming as it does from a company which has been repeatedly slated for doing far too little to protect users' privacy. While it doesn't allow stalkers to do anything they couldn't do before, it does make it an awful lot easier.
Facebook's previously been cited in numerous cases of cyber-bullying and stalking.
Indeed, the company's currently making headlines in Australia because it's reportedly told the mother of a 12-year-old girl that it cannot shut down the child's profile, despite the fact that it's being used by a stalker to intimidate her.