Today Facebook did some modification in navigation bar by addition of news feed counter. It is function is similar as counter of groups/pages activity in left sidebar. Well I'm pretty much sure that it is not that change for which on 13th June 2013 Facebook send breakfast invitations to multiple of media authorities to unfold news of new product on 20th June 2013 in Menlo Park office. But it is possible that this change might be the part of the same series.
The last change in news feed was made on 7th of march in which Facebook redesigned news feed by some massive modifications. The recent addition by Facebook which I liked most is of hash tag. By which users can add context to their threads or can use it to discover more related content.