Use this plist to set up launchd scheduled task to run this script: https://gist.github.com/1339272

me.venj.checkiPhone.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>

    <!-- Contains a unique string that identifies your daemon to launchd.
    This key is required. -->
    <key>Label</key>
    <string>me.venj.checkiPhone</string>

    <!-- Contains the arguments [to exec()] used to launch your daemon.
    This key is required.  -->
    <key>ProgramArguments</key>
    <array>
      <string>/usr/bin/ruby</string>
      <string>/usr/local/bin/myscripts/iphone</string>
    </array>
    
    <!-- This optional key specifies the user to run the job as. This key
    is only applicable when launchd is running as root. -->
    <key>UserName</key>
    <string>venj</string>
    
    <!-- Run every ? seconds -->
    <key>StartInterval</key>
    <integer>1800</integer>
    
    <!-- low priority -->
    <key>Nice</key>
    <integer>20</integer>
    <key>LowPriorityIO</key>
    <true/>
</dict>
</plist>