Battlefield 1943 in the PlayStation 3 version of Battlefield 3, as announced by Sony at E3 2011.
The main issue is that not only did EA renege on its offer, but did so in what gamers are calling "bait and switch". The announcement that there would be no Battlefield 1943 came at the last minute, and the announcement itself was a single post on Twitter. Instead, PS3 gamers will be getting early access to premium DLC (that they must pay for, of course.)
The suit accuses of EA having "misled and profited from thousands of their customers by making a promise that they could not, and never intended, to keep". There are plenty of multiplatform customers who chose the PS3 version solely on the basis of the bonus.
It'll be interesting to see if Electronic Arts whips out the "" EULA clause on the plaintiffs. Stay tuned.