Guerrilla Games has just released patch v1.04 for Killzone 3, and it's a patch which they state will be the first of many in the near future.
Quite a lot of minor things have been fixed/adjusted, for example, everyone now has slightly more stamina and you won't get stuck on players who're mortally wounded when running around.
A ton of bugs have also been fixed, with Guerrilla trying to resolve situations where crashes happen, some glitches with Trophies, and just general stability.
If you want to find out the full list of updates, please check out the official Killzone 3 website.
Source: Killzone 3 Blog