edit: Oh the trailer has been posted already. Here are the availability details: 

Squad Rush Summary

Gamemode: Squad Rush puts a squad of four players versus another squad of four players for a max of eight player matches in this intense one crate/two base infantry only version of the Rush gamemode.

 

How To Access "Squad Rush" at Launch

North America: All customers that pre-order from GameStop (local retail store or website) on Xbox 360 and PlayStation 3 will have an Exclusive Access* for 30 days to play the "Squad Rush" gamemode and any friends they bring with them.  This means you can always play with your friends if you have the Exclusive Access* never forcing you to split from them, plus those that have this Exclusive Access* are a bit more popular...  even if only for 30 days. ;-) *This game mode would be automatically unlocked for everyone after 30 days.

 

Rest of The World: No Exclusive Access, as  this mode would be unlocked day 1 at no extra cost and you can also invite any of your American buddies to play as well.

 

* No Exclusive Access on PC, as this mode would be unlocked day 1 (no extra cost).

Jup - all publishers have to ponder to Gamestop, because their preoders make up for the majority of day 1 sales. Publishers don't dare to screw with Gamestop and always try to be on their good side. They've almost got the entire market cornered in the US - so this will only get worse, until online distribution takes off for good.