THQ has confirmed that the upcoming Metro 2033 downloadable content mentioned earlier is due "in the very near future", and detailed the contents.
The "Ranger Pack" will introduce two new weapons - the Heavy Automatic Shotgun and the Volt Driver, "Miller's signature gun".
You also get "Ranger Mode" game rules. These include standard Ranger mode, where ammo is reduced but weapons do more damage, and Ranger Hardcore, which does away with the HUD.
On top of that you can expect to earn new achievements (worth 250 Gamerpoints on Xbox 360).
There's no specific date for the pack, and pricing will be announced closer to launch.