Need a function for changing saved post_date or post_date_gmt to relative time in wordpress

Straight from my framework as human_time_diff() involves caching.

/**
 * Time since an entry was posted
 * 
 * Adapted from binary bonsai
 * @link    http://binarybonsai.com/code/timesince.txt 
 * @license unknown - original source unavailable
 * 
 * @todo check human_time_diff(); as a replacement 
 * @link http://codex.wordpress.org/Function_Reference/human_time_diff
 * Note: Rarst said there's caching involved with this fn.
 * 
 * @param   (integer) $older_date
 * @param   (integer) $newer_date
 */
function get_time_since( $older_date, $newer_date = false )
{
    // array of time period chunks
    $chunks = array(
         array( 60 * 60 * 24 * 365 , 'year' )
        ,array( 60 * 60 * 24 * 30 , 'month' )
        ,array( 60 * 60 * 24 * 7, 'week' )
        ,array( 60 * 60 * 24 , 'day' )
        ,array( 60 * 60 , 'hour' )
        ,array( 60 , 'min' )
    );

    // $newer_date will equal false if we want to know the time elapsed between a date and the current time
    // $newer_date will have a value if we want to work out time elapsed between two known dates
    if ( $newer_date == false )
    {
        $newer_date = time() + ( 60 * 60 * get_option( 'gmt_offset' ) );
    }
    else 
    {
        $newer_date = $newer_date;
    }

    // difference in seconds
    $since = $newer_date - $older_date;

    // we only want to output two chunks of time here, eg:
    // x years, xx months
    // x days, xx hours
    // so there's only two bits of calculation below:

    // step one: the first chunk
    for ( $i = 0, $j = count( $chunks ); $i < $j; $i++ )
    {
        $seconds = $chunks[$i][0];
        $name = $chunks[$i][1];

        // finding the biggest chunk (if the chunk fits, break)
        if ( ( $count = floor( $since / $seconds ) ) != 0 )
        {
            break;
        }
    }

    // set output var
    if ( $count == true )
    { 
        $output = "1 {$name2}";
    }
    else 
    {
        $output = "{$count} {$name}s";
    }

    // step two: the second chunk
    if ( $i + 1 < $j )
    {
        $seconds2 = $chunks[$i + 1][0];
        $name2 = $chunks[$i + 1][1];

        if ( ( $count2 = floor( ( $since - ( $seconds * $count ) ) / $seconds2 ) ) != 0 )
        {
            // add to output var
            if ( $count2 == true )
            {
                $output .= ", 1 {$name2}";
            }
            else 
            {
                $output .= ", {$count} {$name2}s";
            }
        }
    }

    return $output;
}