Shuhei Yoshida, President of Sony Worldwide Studios, has confirmed that party chat will work between the PlayStation 4 and PlayStation Vita — so regardless of what platform you are playing on, you should be able to talk with friends. The news was revealed on Yoshida's Twitter so we're still awaiting official detail from Sony.
Cross-game online chat has been available on the Vita since its launch; however, it never was supported on the PlayStation 3. Looking ahead, the PS4 was already shown to support cross-game chat. Finally, you can talk to friends no matter what game you're playing.
[Destructoid via Joystiq, Twitter]