The bash variables $@ and $* expand into the list of command line arguments. Generally, you will want to use "$@" (that is, $@ surrounded by double quotes). This will do the right thing if someone passes your script an argument containing whitespace.
So if you had this in your script:
outputfile=$1
shift
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOUTPUTFILE=$outputfile "$@"
And you called your script like this:
myscript out.pdf foo.ps bar.ps "another file.ps"
This would expand to:
gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOUTPUTFILE=out.pdf foo.ps bar.ps "another file.ps"
Read the “Special Parameters” section of the bash man page for more information.