I have had to rename the ATI drivers a second time. Soon there will be driver packages in the repos for ArchCK as well, and I decided it was best to bite the bullet, and make the ati drivers concordant with this new naming scheme, rather than risk user confusion later on.
The new drivers are known as ati-fglrx (kernel module for 2.6.15-ARCH) ati-fglrx-archck (kernel module for 2.6.15-archck) ati-fglrx-utils (xorg7 stuff and tools)
I have also just moved ArchCK and mkinitramfs to extra. If you wish to use fbsplash, you need to install gensplashutils and initscripts-gensplash from community. They are no longer a dependency of mkinitramfs - you must install them yourself. If you already have them installed, then theres no need to worry.
madwifi-ng has been moved into unstable, as it's releases are based on svn snapshots. Enable the [unstable] repo and pacman -S madwifi-ng, or if you use ArchCK, pacman -S madwifi-ng-archck.
My apologies about the ati-drivers rename but it was needed to prevent user confusion later on down the road. The upgrade path isnt too difficult, and is one you can attempt when you are ready, the current ati-drivers have yet to be removed.