The Metal Gear Solid games span across decades, though not in chronological order. This should clear the timeline up.
A remake of MGS3, Metal Gear Solid Δ: Snake Eater promises to be a faithful retelling of the original game, including implementing the original voice acting featuring David Hayter.
Metal Gear Solid 4 was released as a PlayStation 3 exclusive in 2008. It launched to widespread critical acclaim with some pointing to it as one of the absolute best video games ever made.