I have a new engineer on my team this week, and a couple of the first projects he's working on are open source config mgmt. (for basic config files) as well as open source AV.
On the config management front, we're leaning towards Puppet. I have a good friend who uses cfengine on a big server farm, and he loves it. From what I've read Puppet seems to be a newer more modern version, and we don't have a huge farm to manage so I think it would work perfectly for us. Looking forward to learning and implementing it!
With AV we are runnin some tests with Clamwin, and we'll see how well it can pickup incoming viruses uploaded via our Resin application servers. We shall see.
Next project will be bringing a CentOS yum repo locally and patching over the LAN versus the internet, another project I've wanted to get done, but haven't yet completed.