A simple tcp monitor ?
spudlyo: Grab the Nagios plugins tarball, build it on linux, and find the check_tcp program.  Wrap a little shell program around check_tcp that will either do nothing, or fire off your script depending on the return code of check_tcp.  Run this once a minute out of cron.  Make sure these scripts won't stack up, by either setting check_tcp's socket timeout to less than 60 seconds, or have the script initially check to make sure no other of its kind are running.