Modern Warfare 2's first DLC, the "Stimulus Package," but thanks to an Xbox Live Marketplace listing for the map pack, we aren't in the dark anymore as to its contents. The blurb reveals the pack will contain "5 additional action-packed maps," including three all new ones ("Bailout, Storm, and Salvage"), as well as two remakes from Call of Duty 4: Modern Warfare ("Crash" and "Overgrown").
"Bailout" is said to be "a multi-layered apartment complex," while "Storm" is described as "an open industrial park littered with heavy machinery," and "Salvage" is "a snowy junkyard fortified by stacked debris and crushed cars." Presumably, if you're reading about the details of unreleased a MW2 map pack, you already knew that "Crash" is a "war-torn urban environment" and "Overgrown" is set in a large dry creek. No pricing is set, unfortunately, though you can ogle the XBLM listing for now if it makes you feel any better (though we wouldn't suggest it).
[Update: Clarified Stimulus Package DLC date of release.]