According to
Game Informer, Microsoft has announced the development of a new Halo "digital feature" project in partnership with acclaimed Hollywood director Ridley Scott:
343 Industries, Xbox Entertainment Studios and Scott Free Productions are proud to announce a new "Halo" digital feature project to be released later this year. The project will be executive produced by Ridley Scott and Scott Free TV President, David Zucker. Sergio Mimica-Gezzan ("Battlestar Galactica" "Pillars of the Earth," "Heroes") will direct.
Exactly what a digital feature is was not clarified, but we're going to presume its means something similar to the Halo: Forward Unto Dawn series of live action shorts that accompanied the launch of Halo 4.
This latest development is supposedly completely separate to the live action TV series being produced by Stephen Spielberg. More details on both projects are expected at the 2014 E3 expo in June.