This is still not fixed.  On a fresh install of feisty, I still see the following in syslog:

Jul 10 07:35:04 zadok cupsd: Unable to open log file "/var/log/cups/error_log" - Permission denied

Here is the listing for that directory:

[ahawtho@zadok tmp]$ ll /var/log/cups
total 60
drwxr-xr-x 2 root   root    4096 2007-07-10 07:35 ./
drwxr-xr-x 9 root   root    4096 2007-07-10 07:37 ../
-rw-r----- 1 cupsys lpadmin    0 2007-07-06 07:37 access_log
-rw-r--r-- 1 cupsys lp       207 2007-07-05 11:59 access_log.1.gz
-rw-r--r-- 1 cupsys lp       137 2007-07-04 19:10 access_log.2.gz
-rw-r--r-- 1 cupsys lp       134 2007-07-03 08:13 access_log.3.gz
-rw-r----- 1 cupsys lpadmin  144 2007-06-29 13:28 access_log.4.gz
-rw-r----- 1 cupsys lpadmin  124 2007-06-25 00:53 access_log.5.gz
-rw-r----- 1 cupsys lpadmin  843 2007-07-10 07:35 error_log
-rw-r----- 1 cupsys lpadmin  358 2007-07-09 07:35 error_log.1.gz
-rw-r----- 1 cupsys lpadmin  364 2007-07-08 07:35 error_log.2.gz
-rw-r----- 1 cupsys lpadmin  357 2007-07-07 07:35 error_log.3.gz
-rw-r----- 1 cupsys lpadmin  585 2007-07-06 13:16 error_log.4.gz
-rw-r--r-- 1 cupsys lpadmin  484 2007-07-05 11:59 error_log.5.gz
-rw-r----- 1 cupsys lpadmin  110 2007-06-30 22:01 error_log.6.gz
-rw-r----- 1 cupsys lpadmin   95 2007-06-27 09:00 error_log.7.gz
-rw-r----- 1 cupsys lpadmin    0 2007-06-21 23:44 page_log

and cupsd is running as user 'lp':

[ahawtho@zadok tmp]$ ps auxw | grep cupsd
lp       10308  0.0  0.0   4704  1816 ?        SNs  07:35   0:00 /usr/sbin/cupsd
ahawtho  11000  0.0  0.0   2888   776 pts/3    S+   09:10   0:00 grep cupsd

According to /proc/10308, it also is running with group lpadmin:

[ahawtho@zadok tmp]$ ll -d /proc/10308
dr-xr-xr-x 5 lp lpadmin 0 2007-07-10 08:44 /proc/10308/

/etc/cups/cupsd.conf has the lines:

User lp
...
Group lpadmin

But /etc/init.d/cupsys has seemingly conflicting permissions (look for ####):

case "$1" in
  start)
	log_begin_msg "Starting $DESC: $NAME"
        #### Here, we have root:lpadmin, with 3775
	chown root:lpadmin /usr/share/ppd/custom 2>/dev/null || true
	chmod 3775 /usr/share/ppd/custom 2>/dev/null || true
	mkdir -p `dirname "$PIDFILE"`
        #### Here we have cupsys:lp (not lpadmin), but the directory shows lp:lpadmin 
	chown cupsys:lp `dirname "$PIDFILE"`

	# create the logs file since cupsd can't
	for l in access_log page_log error_log; do
	    [ -e /var/log/cups/$l ] || touch /var/log/cups/$l
	    chmod 640 /var/log/cups/$l
            #### Here we have cupsys:lpadmin, with permissions 640, but since cupsd is run as user 'lp', not 'cupsys', these files are not writable
	    chown cupsys:lpadmin /var/log/cups/$l
	done

	if [ "$LOAD_LP_MODULE" = "yes" -a -f /usr/lib/cups/backend/parallel \
             -a -f /proc/devices -a -f /proc/modules \
	     -a -x /sbin/modprobe ]; then
	  modprobe -q lp || true
	  modprobe -q ppdev || true # for ISO-1284 device name detection
	fi

	start-stop-daemon --start --quiet --oknodo --pidfile "$PIDFILE" --exec $DAEMON

	# Correct the permissions after starting the CUPS daemon
	for l in access_log page_log error_log; do
	    chmod 640 /var/log/cups/$l || true
            #### Here again, cupsys:lpadmin, but cupsd is lp:lpadmin.
	    chown cupsys:lpadmin /var/log/cups/$l || true
	done

	log_end_msg $?
	;;

I'd be happy to submit a patch, but I'm not sure which users/groups are correct since there are 2 of each.