This year, indeed...
As you may have heard, the servers for Metal Gear Solid 3: Subsistence's online mode have closed. On the official online support website, Konami said something about thanking the players and hoping they enjoyed it etc.
Metal Gear Solid: Portable Ops is the only other Metal Gear game with Metal Gear Online--and it has already come out in North America last year. So unless there are plans to put the servers back up with something that would warrent it being "new," this could be a hint that Metal Gear Solid 4: Guns of the Patriots will, indeed, be released sometime this year in North America.
Thanks goes to MGS Unofficial Site for the information
LINK: MGS Unofficial Site