Will they? Won't they? It seems Konami can't make up their mind as to whether anybody is actually working on a new Metal Gear game. That's probably why they're trying to hire so many people for the project. The page, part of the official Konami site, calls for people to work on the "latest Metal Gear Solid targeted for high-end consoles and PC," as well as engineers to work on next-gen technology for the FOX engine.
What could it possibly be about? Simply put – Big Boss. The page linked above contains a picture of a "classified" envelope and, underneath, the words "do not click here." Putting the entire internet at risk (who knows what could have happened?), I clicked on the folder and a picture of Big Boss appears. Most interestingly, the page calls for people with an experience of PS3, 360 and PC, hinting that the next big Metal Gear game could be multi-platform, following in the footsteps of Rising.
Now that this has so intentionally been let out of the bag, I think it's fair to say we'll be hearing something a little more concrete about the next Metal Gear over the next few weeks.