Comment 8 for bug 870560

Actually, on closer inspection I found the place where a fglrx installation and an fglrx-updates installation log (jockey.log) differ:

fglrx log excerpt:
---------------------------------------
DKMS: install Completed.
update-initramfs: deferring update (trigger activated)
Processing triggers for gnome-menus ...
Setting up fglrx-amdcccle (2:8.881-0ubuntu4) ...
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.0.0-12-generic
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place

2011-10-16 12:56:00,782 DEBUG: fglrx.enabled(fglrx): target_alt /usr/lib/fglrx/ld.so.conf current_alt /usr/lib/fglrx/ld.so.conf other target alt /usr/lib/fglrx/alt_ld.so.conf other current alt /usr/lib/fglrx/alt_ld.so.conf
2011-10-16 12:56:00,782 DEBUG: XorgDriverHandler(%s, %s).enabled(): No X.org driver set, not checking
---------------------------------------

fglrx-updates log excerpt:
---------------------------------------
DKMS: install Completed.
update-initramfs: deferring update (trigger activated)
Processing triggers for gnome-menus ...
Setting up fglrx-amdcccle-updates (2:8.881-0ubuntu6) ...
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.0.0-12-generic
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place

2011-10-16 12:54:45,761 WARNING: /sys/module/fglrx_updates/drivers does not exist, cannot rebind fglrx_updates driver <-------------
2011-10-16 12:54:45,849 ERROR: xorg:fglrx_updates: get_alternative_by_name(fglrx-updates) returned nothing
2011-10-16 12:54:46,007 DEBUG: fglrx.enabled(fglrx_updates): target_alt None current_alt /usr/lib/fglrx/ld.so.conf other target alt None other current alt /usr/lib/fglrx/alt_ld.so.conf
2011-10-16 12:54:46,007 DEBUG: fglrx_updates is not the alternative in use
---------------------------------------

So that WARNING line in the fglrx-updates log wasn't there in the fglrx log, and shortly thereafter the installation fails with an ERROR.
I hope that this information may help somebody more experienced with jockey/fglrx to fix that bug.