If you are curious about where microformats and metadata are headed (and haven't checked out RDFa), take a look at the W3C's RDFa in Javascript page. There, you'll find the RDFa Highlight bookmarklet. Save this to your bookmarks and then run it on a page that contains RDFa such as the RDFa Calendar Test Page. View source on that to see how the content is structured into data using some simple attributes.

The implications of standard, structured data that can be easily coded - and extracted - are simply huge. Imagine if, without too much additional effort, the blog entries and other kinds of simple web content that you regularly post could be easily mashed up, aggregated, or saved into local apps.

To understand more, check out Elias Torres' excellent and brief write-up of his Open Data in HTML presentation at XTech 2007.