open(my $handle, "|date") or die("ack - $!");
print '$handle is a pipe', $/ if -p $handle;
print while <$handle>;

__output__

$h is a pipe
Fri Jun 21 17:10:26 GMT 2002

##</code><code>##

echo "foo bar baz" | perl -ne 'print uc'
# is the same as (in terms of content)
perl -ne 'print uc'
foo bar baz
^D