As a Reddit user has discovered, Facebook have begun rolling out the ability to reply to comments, starting a separate thread as seen above. The feature is only, according to Facebook, being tested on 30 pages, however it is expected that this will eventually turn into a wider rollout. Facebook is only testing it for certain locales and according to the Los Angeles Times, a spokesperson from Facebook told them that the feature is being tested on pages for specific individuals. I was able to test the feature on this Facebook Page, via Reddit.
This is a fundamental change to the way the Facebook status update system works and it’ll be interesting to see whether it ever reaches people, and not just pages.