Doh! You would think a (relatively) seasoned Perl Junkie would have noticed that list context blurp. Ok the new code that works is:

#!/usr/bin/perl -w
use strict;

if (my $pid = open(READ, "-|")) {
  print "child said: '", scalar <READ>, "'; ",time,"\n";
  print "child said: '", scalar <READ>, "'; ",time,"\n";
} else {
  $|=1;
  print "hello; ",time,"\n";
  sleep 2;
  print "how are you; ",time,"\n";
}
[download]

gryn@echor:~$ ./testcase.pl
child said: 'hello; 1005597768
'; 1005597768
child said: 'how are you; 1005597770
'; 1005597770
[download]

The buffering is necessary, as you all pointed out. However, with the list context problem in the way, I couldn't figure out where to properly put the (de)buffering until it was fixed.