I'm a fan of micro-content. Drupal has enabled this for years, since it's not "just" a blogging tool. Ideally, formats/standards will arise organically. It's fairly trivial to export a different structured format if the source information is stored in a database. I don't really care much about the h* formats...specialized outputs will either be supported directly by themes, or styled as appropriate by people using them.
Drupal's current event module outputs iCal feeds. I think we're going to add per-item vCal links, as well as maybe an RSS feed with vCal items in the enclosure field. There is an RDF namespace for events that might be useful as well, but by supporting iCal and vCal, you get support for the majority of platforms/users without having to rely on support in the client news aggregator -- the default actions of the local OS take over.
Update: I created an Upcoming.org entry