Does this mean it's not gonna be a locked 60fps? Hope it's close enough.

From Spanish gaming journalist's Twitter account:

https://twitter.com/javi__andres

Fingers crossed.

It's starting to become a common option on PS4, FFXIV and inFamous Second Son has this option to lock frame as well. But I believe is not needed to change anything, it will play smooth enough.

Of course it's not locked at 60 fps. The PS4 is a console, not a super computer.
Gonna enjoy the outcry when people realize that UC4 will also not be locked at 60fps.

The option wouldn't be there if the framerate was locked at 60. What would be the point of lowering it to 30, if it was locked at 60 from the get go?

Because some people, including some within Naughty Dog, prefer the slower, more cinematic feel of 30. 

I must be the only person who thinks this a great idea. Except for FPS and racing games, 60FPS just looks weird and stupid for me. All the movement just doesn't look right.

Cinema is 24fps, not 30. 30fps is TV.

As for people within Naughty Dog prefering the framerate to be locked at 30... Care to provide a link?

I miss the word option in the slide, because it does not seem to be an option. It might be locked 30FPS with no option at all.

Boom.