$ perl.5.6.1  -MO=Deparse -e '$a=$;;print $a'
$a = $;;         # two semicolons, one belonging to the variable,
                 # the other one is a statement separator
print $a;
-e syntax OK

$ perl.5.8.0  -MO=Deparse -e '$a=$;;print $a'
$a = $;          # the separator is missing
print $a;
-e syntax OK

$ perl.5.8.1  -MO=Deparse -e '$a=$;;print $a'
$a = $;          # the separator is missing
print $a;
-e syntax OK