In batch mode, one iteration of top won't display the information that you are interested in. Add the -d2 option to run a couple of iterations, and the second should include the CPU info.

#!/usr/bin/perl
use warnings;
use strict;

open (PIPE, "/usr/local/bin/top -b -d2 |") or die "Cannot open top: $!
+";
while (<PIPE>) {
   if (/^CPU/) {
      print;
      last;
   }
}
close(PIPE);
exit(0);
[download]

I tested this on a Sun-Fire-280 running Solaris 9 and I am not a Unix guru so your mileage may vary. Best of luck.

Updated: removed temporary variable for input line.