Once in a while, pacman gives messages about some system config file, and the creation of either a .pacnew or .pacsave file (or sometimes a .pacorig file). The reason why this happens is because your system upgrade results in conflicting configuration files — pacman is smart enough to realize that it would be very dangerous to simply overwrite your configuration files automatically with the new ones from the newer package(s). A good example is GRUB’s menu.lst file — you certainly would NOT want to delete the old (unupgraded) one, since it holds all your valuable data about which partition to boot from, and as well as any other operating systems you use under GRUB. So, how should you take care of them — after all, the newer config files DO often contain newer settings and options.
The answer: install the yaourt package from AUR if you haven’t already. Then, issue the command yaourt -C. This will take care of all those pesky config files via an interactive shell session. Yaourt will let you view the original config file, and the .pacnew or .pacsave variant of it, using a variety of programs — including gvim and vim. I use gvim because my default colorscheme in vim is too dark for displaying the diffs properly. Simply do CTRL + W, W in normal mode to switch between the two windows (copy and paste to quickly merge long sections).
You should get in the habit of doing yaourt -C every time you encounter a message about a .pacnew or .pacsave.