I subscribe some feed published by wordpress: I found the timezone problem. the post always shown published tomorrow.
current wordpress default pubDate field is localtime + GMT timezone:
<pubDate>Wed, 25 May 2005 09:32:44 +0000</pubDate>
but feed publish in China: it should be
<pubDate>Wed, 25 May 2005 09:32:44 +0800</pubDate>
or convert time to GMT and +0000
<pubDate>Wed, 25 May 2005 01:32:44 +0000</pubDate>