Remote play is a feature that arose during the PS3 era and allowed people with a PSP and later a PS Vita to play their PS3 via a network connection. The same feature also surfaced on the PS4. It was linked to either having a Vita, PlayStation TV or an Xperia phone.
Now it looks like with either a PC or a Mac you’ll be able to play your PS4 via the same method. Naturally, the PS4 needs to be on for this to work and you need a pretty decent network connection for games to be decently playable. However, the fact that Sony is willing to roll this functionality out is interesting. What with the revelation that the PS4 will soon be able to emulate PS2 games, it seems Sony are trying to broaden the feature set of the console.