An invite has reportedly been sent to tech journalists in California inviting them to an event at Facebook company headquarters in Menlo Park. As you can see the invite doesn't go into too much detail about what's going to be on show, just that changes are coming to Newsfeed. Facebook last made changes to the Newsfeed in September 2011, something that didn't go down too well with users.
CNET reports that an alternative version of Timeline has been tried out in New Zealand, a territory that Facebook typically uses to try out in new features. The newer version of Timeline has all post updates appearing in a single column rather than the current two.