You should take a look at "Script Update Checker" http://userscripts.org/scripts/show/20145. It's a few lines of code that you can copy and paste into your GreaseMonkey script that enable it to automatically check userscripts.org for updated versions of the script.

It only takes a minute or two to add it to your script, and then users will automatically be notified whenever you update this script. Please take a look because I think this is a nice feature this script could take advantage of.