Doing a bare install of CentOS 5.3, I noticed that all the cron folders were created, but that cron jobs were not firing. Searching the web, I found a few people with the same problem, but no one seemed to have a fix, until now.
[root@somebox etc]# ll | grep -i "cron"
-rw-r--r-- 1 root root 298 Mar 27 2007 anacrontab
drwx------ 2 root root 4096 Aug 30 23:09 cron.d
drwxr-xr-x 2 root root 4096 Jul 2 20:35 cron.daily
-rw-r--r-- 1 root root 0 Apr 9 2008 cron.deny
drwxr-xr-x 2 root root 4096 Jan 6 2007 cron.hourly
drwxr-xr-x 2 root root 4096 Apr 9 2008 cron.monthly
-rw-r--r-- 1 root root 255 Jan 6 2007 crontab
drwxr-xr-x 2 root root 4096 Apr 9 2008 cron.weekly
[root@somebox ~]# yum info vixie-cron
Installed Packages
Name : vixie-cron
Arch : i386
Epoch : 4
Version : 4.1
Release : 76.el5
Size : 619 k
Repo : installed
Summary : The Vixie cron daemon for executing specified programs at set
: times.
License : distributable
Description: The vixie-cron package contains the Vixie version of cron. Cron is
: a standard UNIX daemon that runs specified programs at scheduled
: times. Vixie cron adds better security and more powerful
: configuration options to the standard version of cron.
[root@somebox ~]# yum install vixie-cron