One of our junior sys admins told me he was trying to figure out how to modify his monitoring script during maintenance windows (the monitoring script is called automatically by the monitoring agent on the box.) I told him to use a "stop file."
At or near the top of your script (a simple bash script,) put a block like this:
if test -f /tmp/do_not_run
Then, during maintenance windows, create the /tmp/do_not_run file and the script will simply exit without attempting to perform any actions against the system. When the maintenance window is over, remove the file and everything goes back to normal.
Video demo of setting up Fedora 16.
This is an open source version of web conferencing, similar to Webex. They have a vmware image of this at http://code.google.com/p/bigbluebutton/wiki/BigBlueButtonVM
These turn-key LAMP stacks come in a variety of applications. Download the vmware image and run it. Once you learn the application flow, you might want to build it from on a fresh LAMP VM image, or customize your own version. If you want to move to production, pay Bitnami a monthly fee and run their customs builds in Amazon ec2.
This is the presentation used for the meeting June 11th 2011.