array (
  'arg1' => 'foo',
  'arg2' => 'some text',
)

<?php

$string = 'arg1="foo" arg2="some text"';

$arr = array();
Function parseargs($matches) { global $arr; $arr[$matches[1]] = $matches[2]; }

preg_replace_callback('/(\w+)="([^"]*)"/', 'parseargs', $string);

echo '<pre>', var_export($arr,true), '</pre><hr>';

highlight_file(__FILE__);

?>