DSOGaming: "Remember the teaser website of Modern Warfare 4? Well, it appears that it was valid as a new poster has appeared (kudos to Insomnia’s Psycho_Warhead for spotting it) today, hinting at an incoming announcement/reveal on March 21st."
Update Title should read "Call of Duty: Modern Warfare 4", not "Call of Duty 4". The poster was most probably present at either PAX East or GDC which is why it is labeled as rumor (incoming reveal is about those events, not for just today. PAX East starts today after all)