When you use cron to call your scripts you probably do this with either cgi or cli version of php.
I haven't done this myself, but here's what I found on php manual page for [man]features.commandline[/man]:
phpnotes at ssilk dot de
22-Oct-2002 10:36
To hand over the GET-variables in interactive mode like in HTTP-Mode (e.g. your URI is myprog.html?hugo=bla&bla=hugo), you have to call
php myprog.html '&hugo=bla&bla=hugo'
(two & instead of ? and &!)
There just a little difference in the $ARGC, $ARGV values, but I think this is in those cases not relevant.