These story of who can do 1080p at 60 fps is ridiculous. Even PS360 can do 1080p at 60 fps easily! It's just a matter of deciding if you want resolution or framerate or more effects on the screen. A 30 fps game allows the double of the time to render a frame and a 720p game has half of the pixels being rasterized than in a 1080p one. Developers lower the resolution and framerate to achieve more effects, objects, lightning sources, etc on the screen.
In a fixed spec machine we always will have the option for these kind of trade-offs. Probably 1080p will be more common than 60 fps, since it results in a visual improvement that is very clear for the user. Now, 60 fps? That won't be that normal. Most users don't care when the game isn't a race sim or fighting game.
About the performance, the info we have is that PS4 has a better GPU and faster memory. So, of course, games will run better on it. It won't be much of a difference, I think we can expect things like 45 fps vs 60 fps, 1080p vs 900p or PS4 versions with more objects on screen or slightly better lightning or textures. For what I have seen by now, it won't be that game changer, but it will be visible. The most important for Sony won't be the more powerfull hardware, it will be the US$100 difference. That is what people care.
