EA and DICE keep on improving Battlefield 3, since every game is bound to have something that needs fixing. Sometimes a patch will fix one set of things, then expose some entirely new things that need to be patched. In the case of Battlefield 3, EA will soon issue a massive 2GB patch that fixes a little bit of everything. You will be able to change the color of the in-game HUD to something more visible (useful for the colorblind) and reassign cycle weapons, plus no longer die in some extreme cases, like running and vaulting over an obstacle into water. There are also plenty of tweaks and bugfixes, like moving of a tank spawn on the Caspian Border map so the tank is no longer destroyed when a tree falls on it. The Tactical Light has been tweaked so it no longer blinds you over a long range, AT mines now are active for 20 seconds after a player dies to avoid infinite mines, decreased accuracy for all weapons on fully automatic firing (burst fire is now more accurate), and an increased mortar reload time and travel time for the shells.
The full list of changes can be viewed at the source or on Battlelog if you own Battlefield 3, and the patch should hit around 8am GMT tomorrow morning.