Facebook asked Eric Olson, the designer of Klavika, the font used for the original wordmark, to design a new typeface.
Ben Barry, a former designer at Facebook, had also proposed tweaks to the Facebook wordmark in 2012 which were approved by the company but never implemented.
The actual Facebook ‘F’ logo isn’t being changed. You’ll only notice the difference where the full name is used.
The new Facebook identity will be showing up across Facebook’s various sites and apps soon, with the large F logo and favicon remaining unchanged.