Change summary (thanks @chrisdoohan):
version="2.0" attribute to the <rss> tag, to allow validation of the feed.<pubDate> element from truncated ISO to RFC-822 (validators were flagging this).atom:link element in the <channel>, for compatibility with various readers. Validators flagged this as a potential issue. Apparently the attributes in that tag help identify the content source, if a feed item has been through aggregators and is being served in a different feed.