I’d be surprised if anyone cares, but my site now supports the hAtom microformat.  At least, I think it does.  I couldn’t find an hAtom validator so I’m not 100% sure I’m conforming to the standard.  But it’s pretty simple so I’m gonna say yes.  As far as I know hAtom is only slightly more supported than RFC 1149.  But I think that’s only because of the recent avian flu concerns.

You won’t notice any difference in the site1 (which is how microformats are supposed to work, after all).  Except for what they call the Datetime Design Pattern.  This is where you stick an abbr tag around a human-readable date, and set the abbreviation’s title attribute to a machine-parsable ISO 8601 timestamp (i.e. “2007-11-26T19:57:00-05:00”).  The problem with this is that now if a user hovers over my timestamp, he sees this very unfriendly tooltip.  This is exactly the opposite of what the abbr tag is supposed to be used for!  (And, more generally, what the title attribute is supposed to be used for.)  There is no reason to display this information to the user.  Surely there must have been a better way.  I’m tempted to make a non-displaying abbr tag for the hAtom “published” date.  An XML parser would still read it regardless of its style, but users wouldn’t have to see this ugly timestamp.