Worked fine on Suse Linux 11.3 64bit. Here my test script:

#!/usr/bin/perl
use Term::ReadKey;
use Time::HiRes qw(time);

    ReadMode 3; # 'noecho';

while (1) {
    my $key;
    my $wait_until = time + 3;
    while ( time < $wait_until ) {
        $key = ReadKey( -1 );
        if ( defined $key ) {
        print STDERR "keystroke $key\t";
         }

    }
    
    print "Something\n";
}
[download]

Be prepared to type in perl -e 'use Term::ReadKey; ReadMode 1;' blindly after executing the script to gt a working terminal again ;-)

Maybe some security feature (SELinux or AppArmor) gets in the way on your machine