He encontrado por fín una función que va!
sería algo así:
Código PHP:
function texto_a_url($text){
// pad it with a space so we can match things at the start of the 1st line.
$ret = ' ' . $text;
// matches an "xxxx://yyyy" URL at the start of a line, or after a space.
// xxxx can only be alpha characters.
// yyyy is anything up to the first space, newline, comma, double quote or <
$ret = preg_replace("#([\t\r\n ])([a-z0-9]+?){1}://([\w\-]+\.([\w\-]+\.)*[\w]+(:[0-9]+)?(/[^ \"\n\r\t<]*)?)#i", '\1<a href="\2://\3" target="_blank">\2://\3</a>', $ret);
// matches a "www|ftp.xxxx.yyyy[/zzzz]" kinda lazy URL thing
// Must contain at least 2 dots. xxxx contains either alphanum, or "-"
// zzzz is optional.. will contain everything up to the first space, newline,
// comma, double quote or <.
$ret = preg_replace("#([\t\r\n ])(www|ftp)\.(([\w\-]+\.)*[\w]+(:[0-9]+)?(/[^ \"\n\r\t<]*)?)#i", '\1<a href="http://\2.\3" target="_blank" rel="nofollow">\2.\3</a>', $ret);
// matches an email@domain type address at the start of a line, or after a space.
// Note: Only the followed chars are valid; alphanums, "-", "_" and or ".".
// Remove our padding..
$ret = substr($ret, 1);
return($ret);
}
Voy a ver si puedo conseguir que los @nicktwitter los pase a un enlace a <a href="http://twitter.com/nicktwitter">Nicktwitter</a>