Seihyouken on 10 June 2009
Portable Ops is canon. It always has been and it almost certainly always will be. It was a sequel to MGS3 in the same sense that Ninja Gaiden: Dragon Sword was a sequel to Ninja Gaiden and Metroid Prime Hunters was a sequel to Metroid Prime. If you want to call all of those games spin-offs then they are all spin-offs.
What is true is that Metal Gear Solid: Peace Walker will be the first direct followup to Metal Gear Solid 3 that Kojima is heavily involved with.
