Actual code segment from ExpressionEngine, found within /expressionengine/expressionengine/libraries/Localize.php, in convert_human_date_to_gmt(). I tracked it down in an effort to fix the software's inability to store dates from prior to 1902 <http://ellislab.com/forums/viewthread/74033>, which they had blamed on everybody but themselves.

ee-dates

if ($year < 1902 OR $year > 2037)
{
	return $this->EE->lang->line('date_outside_of_range');
}

I think that's pretty easily addressed by PHP's PHP_INT_SIZE constant, which exists for just this purpose:

if ( (PHP_INT_SIZE == 4) && ($year < 1902 OR $year > 2037) )
{
    return $this->EE->lang->line('date_outside_of_range');
}

That way, only folks on 32-bit environments are bound to the range, while the rest of us can have proper dates.