10 GB /var/log/messages file

Again fedora!
After the installation of linux kernel and linux operating system, I installed some libraries, some small applications that I usually use… I have a partition for Fedora 9 with 14 GB size. After installing all those softwares, when I rebooted the system today, the gdm was not starting. GDM kept on restarting and I could not take a user session by pressing ALT + CTRL + F1. hmm… So added single at the kernel argument in the grub, and got the shell.
To my surprise I saw that df -a is saying the partition is 100% full..!. I just installed a few application and not anything for 14 GB..
So tried to figure out who is taking the full diskspace and I caught him.
/var/log/messages
Yes!
$ls -l messages
-rw——-+ 1 root root 10450239682 2008-05-27 20:39 messages

Ok, 9.7 GB. so who is writing to messages?
$tail -n 100 messages
This gave me some hint. Some sample lines from messages file:
May 27 20:39:23 thottingal gdm-simple-slave[2523]: DEBUG: GdmSignalHandler: Adding handler 5: signum=8 0x804c520
May 27 20:39:23 thottingal gdm-simple-slave[2523]: DEBUG: GdmSignalHandler: Registering for 8 signals
May 27 20:39:23 thottingal gdm-simple-slave[2523]: DEBUG: GdmSignalHandler: Adding handler 6: signum=1 0x804c520
May 27 20:39:23 thottingal gdm-simple-slave[2523]: DEBUG: GdmSignalHandler: Registering for 1 signals

GDM was writing all debug messages to the /var/log/messages. can somebody help me to figure out what is wrong with my GDM?
(the [debug] section of /etc/gdm/custom.conf is empty)