icalendar - Most common standard to provide a feed of upcoming events via web -

What are the common ways / official parameters for surfacing the event or calendar data?

My use case is that I want to collect event information in a single calendar or event entry from many different websites (it is on an intranet, we have control over all the websites). I want to ask websites to present their data in a certain format so that I can consume it.

Things I've seen in:

• iCalendar
• hCalendar (microformat) - embedded in webpages, but then a web crawler is required is?
• RSS - There is no clear standard to embed time-specific data (Event proposal that is currently in 'Proposed')
I think the place where hCalendar becomes useful.

Calendar data form a syndication feed of updates Submit