Dylan Jobe, President of LightBox Interactive, has announced through the official PlayStation blog that all of the future map packs for the newly released Starhawk will be free!
After a long discussion between LightBox Interactive and Sony Santa Monica, they came to the decision that the paid map packs for Warhawk splintered the online community too much. After three expansions, the "player community was pretty fractured." So in response, they will be giving away all upcoming map packs for Starhawk.
They will still be offering paid DLC content in addition to the free map packs, but they're still combing through player feedback for what that DLC should be.