I keep a copy of the FreeBSD source and ports repository locally on disk so its possible for me to work offline and still be able to review the revision history of a file or views diffs. I have been running csup from the root crontab at night to keep my local copy fairly up to date.
However, I rewrote the script to be a job that is executed by periodic and then have the output of csup included with the daily run output emails I get each morning so I can quickly see the changes to the ports tree.
Place a copy of 600.csup into /usr/local/etc/periodic/daily (you may have to create this directory if it does not exist)
To enable the script, add the following to /etc/periodic.conf.local (which may need to be created if it does not exist)
One thing to keep in mind is that all scripts the get executed by periodic daily are run at 3:01am localtime so it will cause a huge spike in traffic if you have lots of machines connecting to the same csup server all at the same time.