if you want to create a "serverscript" in php you don't need to keep it running all day and night long. It is more than enough to call the script by it's url.
if the script needs to run a lot longer then the default execution time, you can use
so your script will time out after 5 minutes. Feel free to change the seconds
Just a reminder: dreamhost takes heavy load scripts very seriously!
slauson.dreamhost.com rocks! (so does my site :))