I think this can be achieved with proper db query. But if you need Perl script to do this, use something like this:

$refvalues=
[['1', '2008-04-04 17:30:01'],
....
['1', '2008-04-04 22:10:02']];

sub calcdiff
{
  ($d1, $d2) = @_;
  return ???
}

$is_in_state_0 = 0;
$start_date = '';
$end_date = '';
for(@$refvalues)
{
    if($is_in_state_0)
    {
        if($$_[0] eq '1')
        {
            $end_date = $$_[1];
            $is_in_state_0 = 0;
            print 'status 0 detected between '.$start_date.' and '.$en
+d_date.' => '. calcdiff($start_date, $end_date)."\n"
        }    
    }
    else
    {
        if($$_[0] eq '0')
        {
            $is_in_state_0 = 1;
            $start_date = $$_[1];
        }
    }
}
[download]

And here you will find description how to fill calcdiff() function