Cross-platform play has been a dream for many years between PS4 and Xbox One, but PS4 has been resisted. Microsoft first announced support for cross-platform play at E3 2016. In a surprise announcement yesterday, Epic Games said that Fornite will support cross–play and cross-progression between the PlayStation 4, PC, iOS, Mac and Android (when it's released). Absent from the list was Xbox One, but Microsoft has provided confirmation to The Verge that the company is working with Epic Games to bring this feature for its users in the future.
“We have been working closely with the team at Epic Games for some time to bring this functionality to all current and future versions of Fortnite and expect it to be available on Xbox along with other platforms,” says a Microsoft spokesperson. “Microsoft has long been a leading voice in encouraging the adoption of cross-platform play and the potential of connecting players across PC, mobile and all consoles.”
The Verge says that Microsoft hasn't specifically confirmed Fornite players will be able to cross-play between PS4 and Xbox One, but will have some cross-play support in ole Xbox and other platforms the game is on.
If you're playing Fortnite on iOS and Android, for example, you'll be able to play against PS4, PC, and even Mac players. Matchmaking will apparently be opt-in, and will be primarily focused around letting groups of friends play with each other. If you're on your phone, for example, playing against skilled PC players will likely not give you a good experience.