Well this is a turn up for the books, after “a comprehensive evaluation process” Sony have decided that cross-platform play is viable on PlayStation 4 for select third party games, with Fortnite being the first. An “open beta” is out now allowing PlayStation 4 gamers to battle against those on Android, iOS, Nintendo Switch, Xbox One, Microsoft Windows, and Mac operating systems.
“For 24 years, we have strived to deliver the best gaming experience to our fans by providing a uniquely PlayStation perspective,” said John Kodera, President & CEO of SIE. “Today, the communities around some games have evolved to the point where cross-platform experiences add significant value to players. In recognition of this, we have completed a thorough analysis of the business mechanics required to ensure that the PlayStation experience for our users remains intact today, and in the future, as we look to open up the platform.”
Assuming the beta goes well we can expect further games to get cross-platform play, Rocket League, Overwatch, and Minecraft would probably near the top of the list. Of course, PlayStation has had cross platform play before but only with PC and mobile players.
I’ve had a quick look on the store and their doesn’t appear to be a specific beta for cross-platform Fortnite so presumably it’s merged in with standard game as an update.
UPDATE: The official Xbox account seems impressed
Marvel: "Infinity War is the most ambitious crossover event in history"
— Xbox UK (@xboxuk) September 26, 2018
Source: PS Blog