Binary to Decimal conversion using the BCMath extension..

<?php

function BCBin2Dec($Input='') {
  $Output='0';
  if(preg_match("/^[01]+$/",$Input)) {
    for($i=0;$i<strlen($Input);$i++)
      $Output=BCAdd(BCMul($Output,'2'),$Input{$i});
  }
  return($Output);
}

?>

This will simply convert from Base-2 to Base-10 using BCMath (arbitrary precision calculation).

See also: my 'BCDec2Bin' function on the 'decbin' document.
Enjoy,
Nitrogen.