In Red Hat Enterprise Linux 4, 15 services in system space had confined SELinux domains defined. In Red Hat Enterprise Linux 5, over 200 processes are confined by SELinux. The improved SELinux policy is much more precise in how it governs the operation of these services. It’s far less likely that a Red Hat Enterprise Linux 5 system space process will be compromised or encounter an error caused by an SELinux policy not handling the specific requirements (e.g., file or directory access) of a service.
This is just a small snippet from the article, which I have not had time to read in it's entirety. Not a huge fan of RH software, but credit is given where credit is due.