How does cron internally schedule jobs?

A few crickets heard in this question. Good ‘ol RTFC with some discrete event simulation papers and Wikipedia:

http://en.wikipedia.org/wiki/Cron#Multi-user_capability

The algorithm used by this cron is as
follows:

1. On start-up, look for a file named .crontab in the home directories of
   all account holders.
2. For each crontab file found, determine the next time in the future
   that each command is to be run.
3. Place those commands on the Franta-Maly event list with their
   corresponding time and their “five
   field” time specifier.
4. Enter main loop:
   1. Examine the task entry at the head of the queue, compute how far in the
      future it is to be run.
   2. Sleep for that period of time.
   3. On awakening and after verifying the correct time, execute the task at
      the head of the queue (in background)
      with the privileges of the user who
      created it.
   4. Determine the next time in the future to run this command and place
      it back on the event list at that time