From the PS Blog:
"Napalm & Cordite, the new downloadable content pack for Killzone 2, contains two exciting new multiplayer maps: Suljeva Cliffside, which takes place on the rocky outskirts of the Suljeva mining village; and Arctower Landing, which revisits the Arctower defense posts of Blood Meridian.
On top of that, the DLC pack allows you to wield a pair of weapons which were previously accessible only through the single player campaign!"
" Napalm: The VC1 Flamethrower
Found in the Suljeva Cliffside map, the VC1 Flamethrower projects an ignited stream of flammable liquid at high pressure. Consisting of low-octane gasoline and an unidentified component indigenous to Helghan, this form of Napalm is extremely effective for clearing out enemy trenches and bunkers.
Cordite: The Boltgun 4400
Also known as "The Handyman", the semi-automatic Boltgun 4400 can be picked up in the Arctower Landing map. It uses Cordite to propel metal bolts at an extremely high velocity, often pinning its targets to walls and other objects. In addition, each round contains a time-delayed explosive charge – so if impalement doesn't finish the target off, the ensuing explosion will.
Napalm & Cordite – an explosive cocktail
Both of these weapons radically alter the Killzone 2 multiplayer dynamic, delivering an experience that's as fresh as it is intense. If you're a veteran Killzone 2 online player looking to mix it up, or if you simply liked wielding these weapons in the single player campaign, Napalm & Cordite is your ticket. Look for it on the PlayStation Store July 23rd!"
There is also a trailer in the link.