Tag system similar to that of Flickr

I needed this code for a "tag system" I was making. Something like when entering tags for an image on Flickr. It extracts all the words and keeps quoted phrases together.

[php code]
$pattern = '#"([^"]+)"|([^"\' ,]+)|\'([^\']+)\'#';
preg_match_all($pattern, $string, $matches);

foreach ($matches[0] as $tag)
{
    echo $tag . "
";
}
[/php code]