BioShock 2's add-on, dubbed "Rapture Metro Map Pack" and priced at 800 Microsoft Points / $10, adds six new multiplayer maps along with a new multiplayer rank of fifty, two additional masks, three more achievements and a "Kill 'Em Kindly melee mode."
It's not known if this content is already on the disc, as the last batch of BioShock 2 DLC was, but given 2K Games' previous explanation, it's likely that at least some of it is. nope
Just Cause 2's "Black Market Aerial Pack," meanwhile, brings "a jet-sized set of new items"-- including the F-33 DragonFly Jet Fighter, Dual Parachute Thrusters and Multi-lock Missile Launcher--in exchange for 160 Microsoft Points / $2.
Thus far, the above prices and dates only apply to Xbox 360, though don't be surprised if the content hits PC and PlayStation 3 around the same time at the same price.