Sony's continued support of PhyreEngine is noteworthy because it initially developed to make cross-platform development easier from Xbox 360 to PS3. While Xbox 360 used a more familiar development environment, the Cell chip in PS3 complicated matters quite a bit. Various third-parties used PhyreEngine to make multiplatform games, notably Dark Souls (pictured) and GRID.
PhyreEngine expanding to PS4 should make it easier for developers to create cross-generation games that run on Vita, PS3, and PS4. Although not mentioned in Sony's announcement, PhyreEngine will presumably (eventually) support the next Xbox system. Sony's continued investment in PhyreEngine may seem strange, considering how PC-like PS4 is, but it's a free tool that devs will undoubtedly appreciate.
Developers can find out more on the SCE dev page.