Molotov Spring Released
If you can't catch the new content from the trailer alone, the full changelog has all the details. There is plenty of new stuff, including two "new" maps that were available before the launch of the game, but were removed because the developers weren't happy with them. These two are Buhriz and Revolt (formerly known as Uprising). The two maps are essentially the same at their core, but have been reworked with new routes, more buildings to enter, and more stuff overall. Several other, already available maps have also gotten the same treatment.
Then you have the new game modes. Four in total.
Infiltrate': a variation on the old Capture-The-Flag mode.
Occupy: a variation on King-Of-The-Hill.
Flashpoint: Each team has two weapon caches to protect while destroying the enemy's, and a single capture-point in the middle of the map.
Vendetta: One player on each team is selected to be Team Leader. Capture points with your team leader or kill the enemy's leader to win.
You've also got the new FN FAL combat rifle, the incendiary grenades and Molotov cocktails, some new scopes, a retextured foregrip for the AK rifles, along with a reworked cooperative system that includes both AI and level redesign, crash fixes, gameplay balancing, and other minor bits and bobs.
The update is out now, and should automatically start downloading on Steam, because it's free to anyone who owns the game.