Eurogamer tv interviewed the game director and he said that they had intended to release Wipeout as a 1080/30 game.
However they had problems with PSN integration and Sony's internal epilepsy tests, so they decided to shoot for 1080/60 and include trophies and other stuff, whilst they tackled the other issues.
Are there any other 1080/60 games on PSN?
I'm almost 100% positive that the game has been 1080p/60fps since it's very first announcement.
That said, another 1080/60 game on PSN that most folks seem to forget about is Calling all Cars. For 2D games, there's PJE and PJM. I also think flOw is 1080p, but I'm not sure of the frame rate (though I think it's 60).