Ok, here is a question for proponents of the Atom format. Why, oh why do you need to have so many different possible data elements for an entry? It seems like every time I find a new Atom feed to test it has specified its published date in a new a novel way. Here are the different date elements that I have encountered so far:

Looks like Google is pushing Atom (a standard that "competes" with RSS) with the launch of the Google Groups2 beta. They have added Atom feeds for thousands of Usenet groups. Here's where you can link to one such feed.