Functionally, yeah. It combines manipulation of both flags and Game Moments, along with the delightfully and appropriately named Yuffie warp that lets you time-travel your current party into any other save file you have.

The individual techniques have been around for a while, but they've finally put all the pieces together to get a fully functioning character back in your party in the Forgotten Capital - literally the start of disc 2, right after she dies, and useable for the entire rest of the game. Pretty cool.