I don't know if you guys noticed but this October is the Internet Storm Center's Cyber Security Awareness Month.
The whole month's tips are a good read, so visit http://isc.sans.org
for some informative material.
In particular, Cyber Security Awareness Tip #19: Linux tips
covers Linux security. I did take it upon myself to contact them to offer our forums as a Linux security resource. Most of what was posted yesterday has already been covered in our forum but it never hurts to read some of this stuff again.