This seems to work, combining hex and chr - I'm sure it could be shorter:

use strict;
use warnings;

while(<DATA>) {
   chomp;
   my @hex_chars = split;
   map { print chr(hex($_)); } @hex_chars;
   print "\n";
}

__DATA__
48 65 6c 6c 6f 2c 20 77 6f 72 6c 64 21
[download]

Output:
Hello, world!