Not sure if you mean that it has to COPY the logfile (and hold it as evidence, if we find errors), or just be able to log rotate, so you can look to logs of days past.
Just know you can send the log to another computer with Rsyslog or Syslog-ng for a centralized logging (and centralized monitoring with additional tools).
As for the monitoring, do you mean realtime, or just check each 5 minutes or so for errors. If the latter, there is this nice perlscript you can use standalone it is called check_log3.pl (details)
You can get the required utils.pm from the nagios-plugins tarball.