Playstation plus member will have access to the mortal kombat 9 demo on Mar 8th, one week later regular psn member will have access. 
 
Source ->  http://blog.us.playstation.com/2011/03/03/coming-to-playstation-plus-exclusive-mortal-kombat-demo-psn-gamers-choice-award-winners-and-prince-of-persia-full-game-trial/

It's also worth noting that this is a different build than the one going to PAX, but probably the same one on the Truck Tour, meaning it's likely not the latest build, let alone the final one. X360 demo is coming "eventually," too. For anyone too lazy to click the link, here's what you get: 

The demo includes four playable characters: Scorpion, Sub-Zero, Johnny Cage and Mileena, along with their Fatalities and X-Ray Attacks; two environments: The Pit and The Living Forest; single player and one-on-one versus modes; and stereoscopic 3D support.    

Looks like Jeff might get a PS+ subscription after all. 

No word on a 360 demo beyond 'eventually'?

So someone is finally going with PS3 first.

" No word on a 360 demo beyond 'eventually'? "

" @Twitchey:  Not to sound like a fanboy but it seems MK is favoring ps3, every time i have seen it it been on ps3's and the whole kratos thing . "

It's marketing dollars, end of story. Sony kicks some money their way so they have something extra for their platform, or they get to make headlines about having the demo early (and in this case sell PS+ subs). MS tosses money at Bethesda and Activision for the same reasons. It's sometimes easy to forget, but video games are a money making industry, and companies will do what they need to do to make more of it. That rarely turns out good for the fans, though.

Just enrolled in the playstation plus program for the first time. Seems cool, and worth the $18 every 3 months. Getting some free downloadable games, free premium themes, and early access to demo's. Can't wait for Tuesday, I'm going to play the shit out this MK demo. Mortal Kombat releases April 19th, a day after the Gears 3 beta comes out. That's a better combo than Cocaine and porn stars; well, almost.

Signed up to the PS+ this morn. Day off tomorrow for added bonus...  now we play the waiting game..

Just signed up a few days ago. Lets do this!

Cannot wait for that. I thought I was going to have to wait until PAX to get my hands on it. @People who are just now signing up for PS+: Download Stacking Its a great game and you don't even have to pay for it.

saw it sitting on the PSN store....so is it good (redundant question)?  Even tempted me slightly to sign up for Plus...then I saw it was 18 bucks for 3 months and thought...nah.  Sign up and then be a b*tch to try to shut it off like Xbox Live probably.

The demo convinced me to get the game. Seriously awesome. Really fast, easy to understand, and reminds me of MK2 (you know, the good one).  I was kicking ass with Johnny Cage in no time. Super impressive to see the game in action. Also, it's a weird thing, but there's no load in between rounds, the person who lost just gets up and the bars refill. It's a small touch, but it makes the game feel really really intense. No break until someone is DEAD.

PSN Plus members only? That's dumb. Hopefully someone puts it online sometime soon so we don't have to wait another week to download it.

i finally understand what jeff and brad are talking about. liked the old 3d games but this one flows really well in terms of combos and fighting mechanics. 
 
also that trailer at the end is so fucking good

" PSN Plus members only? That's dumb. Hopefully someone puts it online sometime soon so we don't have to wait another week to download it. "

The demo is a lot of fun. I can't wait for the full game.

" @RE_Player92:   50 dollars to play a demo?  lol "

" @MindChamber said:

" @RE_Player92:   50 dollars to play a demo?  lol "

You are 26 posts into your life here at Giant Bomb. Stop trolling while you are new. "

Demo is pretty good but some of the commands for the moves are too rigid.
 
Maybe Marvel's flashiness got to me but it doesn't look all that impressive from a visual standpoint either. I know it's meant to be cheesy but the costumes feel like they dropped out of a kids doodling book.
 
I dunno if I want to drop a full $60 into this.... Maybe I'll wait for an Amazon sale or something.

The demo comes out for everyone in like a week or 2....so not that big a deal for people that a miffed.  Of course, I'd love to play it NOAAAAW.   
 
who are the playable characters?  Everyone always has love for MK2 and not 3....MK3 was my favorite, loved the combo system and the ability to charge.

Can't seem to access it on the UK ps plus...    and now i can't connect to the network altogether...  *epic sigh*

 
Cannot wait for this game. 

What are the combinations keys to do a fatality?

Bah, fatalities must be one button press . I want cool animations while playing! 

it looks like it will be good, interesting to hear Ed Boon say the all players should be happy with the package, no matter the console...
 
i still cant see what character that Microsoft can offer to match Kratos though....