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To parse a WKB point in PHP, use the unpack function. It's similar to Perl's except that each format string has a label, and is separated from the next by a slash. The result is an associative array using those labels:

<?php
// $wkb is the value retrieved from MySQL using AsBinary(g)
$geometry = unpack(corder/Ltype/dlatitude/dlongitude, $wkb);
if ($geometry['type'] == 1) {
    $latitude = $geometry['latitude'];
    $longitude = $geometry['longitude'];
}
?>

You can also unpack a polygon or a collection (e.g. Multipolygon) as follows:

<?php

//Step 1 - get number of elements
$query1 = "SELECT NumGeometries($geom)from ......" ;
$result1 = mysql_query($query1);
$row1 = mysql_fetch_row($result1);
$N = $row1[0]; //number of polygons in the Multipolygon

//Step 2 - loop through each polygon 
$n=1;
while ($n<=$N){
$query = "SELECT AsBinary(GeometryN($geom,$n))from ....."; 
//returns a single POLYGON from a MULTIPOYGON
$result = mysql_query($query);
if($result){  
  while ($row = mysql_fetch_array($result, MYSQL_NUM)) {
  $geometry = unpack("corder/Ltype/d*", $row[0]);
   $i=2;
   while($i<count($geometry)){
   echo $geometry[$i]."<br>";
   $i++;
   }
  }
 }
$n++;
}
?>

Hope it helps as it took me a little while to figure out how to extend the excellent unpack example given by Michael

Adding to the two other examples, here is how to parse a LINESTRING:

<?php
// $wkb is the value retrieved from MySQL using AsBinary(g)
$geometry = unpack(corder/Ltype/Llength/d*, $wkb);
if ($geometry['type'] == 2) {
    for ($i = 1; $i < $geometry['length'] * 2; $i += 2) {
        $latitude = $geometry[$i];
        $longitude = $geometry[$i+1];
    }
}
?> 

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