I'm fond of:

sub isBalanced {
    my $text= shift;
    my $brace= @_ ? shift : "{}";
    my $start= substr( $brace, 0, length($brace)/2 );
    my $end= substr( $brace, length($brace)/2 );
    0 while $text =~ s/\Q$start\E[^\Q$brace\E]*\Q$end\E//g;
    return $text !~ /[\Q$brace\E]/;
}
[download]

or even

sub notBalanced {
    my $brace= 1 < @_ ? $_[1] : "{}";
    my $start= substr( $brace, 0, length($brace)/2 );
    my $end= substr( $brace, length($brace)/2 );
    my $depth= 0;
    for(  split /[^\Q$brace\E]*/, $_[0]  ) {
        if(  index($start,$_)  ) {
            $depth++;
        } elsif(  index($end,$_)  ) {
            return -1   if  --$depth < 0;
        }
    }
    return $depth;
}
[download]

modifying these to allow doing something with the matches is left as an exercise (as is testing). (:

        - tye (but my friends call me "Tye")