Use ISO 8601 encoding for the lastmod timestamps and all other dates and times in this protocol. For example, 2004-09-22T14:12:14+00:00.

If you wish, you can omit the time portion of the ISO8601 format; for example, 2004-09-22 is also valid. However, if your site changes frequently, you are encouraged to include the time portion so crawlers have more complete information about your site.

For static files, this is the actual file update date. You can use the UNIX date command to get this date:

For many dynamic URLs, you may be able to easily compute a lastmod date based on when the underlying data was changed or by using some approximation based on periodic updates (if applicable). Using even an approximate date or timestamp can help crawlers avoid crawling URLs that have not changed. This will reduce the bandwidth and CPU requirements for your Web servers.

看了半天，看不出什么道道，想想再作个试验，把SITEMAP.PHP里面的

function gettzdtime ($rawtime) {
 $p=date("Y-m-dTH:i:s", $rawtime);
 $tzd=date("O", $rawtime);
 $p.=substr($tzd, 0, 3).':'.substr($tzd, 3, 2);
 $p=str_replace('+08:00','+00:00',$p); //我觉得好像就是+0和＋8的区别？试一试吧
 return $p;
}

居然成功了：http://www.shengfang.org/blog/sitemap.php Sitemap Index  5 hours ago  9 hours ago  OK  ago时间不对是因为我提交了好几次 ：）