Kotaku reports that the lawsuit, filed by Edelson McGuire, focuses not only on EA's failure to make good on SCEA president Jack Tretton's announcement at E3 in June, but on the publisher's failure to communicate the change in plans to prospective purchasers, who chose to buy the game on PS3 instead of other platforms in good faith.
In fact, EA did not officially announce that Battlefield 1943 would not be included in PS3 copies of Battlefield 3; it was explained on Twitter, in response to a user query, on the day Battlefield 3 was released in North America.
Edelson McGuire further criticises EA for its Twitter claim that "in lieu of 1943 being available on disc for PS3 customers, EA has made all BF3 expansions available early to PS3 customers," because early access to DLC packs had previously been announced. The suit says that EA "misled and profited from thousands of their customers by making a promise that they could not, and never intended, to keep."
In terms of damages, Edelson McGuire told Kotaku that all they are after are the free copies of Battlefield 1943 that customers were originally promised.