The MGS collection is out in November this year, while the ZoE collection comes out some time next year.Both collections have been optimized and rebuilt for the PlayStation 3 and Xbox 360, with new user interfaces for the HD resolutions, redrawn art, brand new Trophies/Achievements, right analog stick and rumble support, and improved audio.
EDIT - There's also a Silent Hill collection coming.
For the nostalgic, Konami has bundled Silent Hill 2 and 3 into an HD package called Silent Hill Collection. These two titles are getting the high-definition upgrade, so a whole new audience can enjoy these horror classics. No release date has been announced.