Metal Gear Solid HD Collection will indeed run at a slick 60 frames per second.
After sharing images of the Metal Gear Solid: Peace Walker remake, Hideo Kojima tweeted, "60 frames per second in HD... it's the best! Say peace!" Kojima Productions' Jiroo Tsubuyaki also confirmed the frame rate in a different tweet.
As Andriasang notes, Peace Walker marks the final game in the collection to benefit from a doubled frame rate. Kojima already confirmed the same for Metal Gear Solid 3: Snake Eater -- and Metal Gear Solid 2, it turns out, always ran at sixty frames per second, even on the PlayStation 2.
We suppose that explains Raiden's ... uh ... smoothness.