During a roundtable interview Sony Worldwide Studios head Shuhei Yoshida stated that the PS4 will output 4K videos and photos, but not 4K games. Via IGN:
“The PS4 supports 4K output, but only for photos and videos — not games. PS4 games do not work on 4K.”
ArsTechnica interpreted Yoshida’s comments as meaning that 4K resolutions for games wouldn’t become available until the generation after the PlayStation 4. IGN reports that “Yoshida says a single console cannot natively run games in the high-resolution format.”
So there you have it: PS4 may play 4K video from upgraded blu-rays or connected media storage devices, and will be able to display 4K photos, but 4K games are seemingly not in the cards.
The question of whether the PS4 will be capable of outputting games at frame rates higher than 60 fps remains to be answered, although Wedbush Securities analyst Michael Pachter thinks it will be capable of rendering games at up to 240 fps.