It's been rumored for a long while, and the PlayStation blog just confirmed it, a Mortal Kombat (2011) demo will be available on the PlayStation Network for PlayStation Plus members on March 8th, 2011. Yes that's next week! PlayStation Plus is a premium version of the PlayStation Network that costs $18 for 3 Months, or $50 for a year. After one week it will be available for non-Plus subscribers and eventually will be available for Xbox 360 users.
It's likely this version is also the same version that will be available at the Mortal Kombat Truck Tour that is starting to tour the country today. It's already known that the PAX East Demo is different which leads us to believe that this is similar to the version going on tour. We'll known soon enough though.