There was a time, about 5 years ago, when I assumed that microformats
were the way to go and spent a bit of time looking at hCalendar for
representing iCalendar-formatted event information.

http://microformats.org/wiki/hcalendar

Not long after that, there was a lot of talk about RDF and RDFa for
this same purpose. Now I was confused as to whether to change my
strategy or not, but RDF Calendar seemed to be a good idea. The latter
also was nice because it could be used to syndicate event information
via RSS.

http://pemberton-vandf.blogspot.com/2008/06/how-to-do-hcalendar-in-rdfa.html
http://www.w3.org/TR/rdfcal/

These days it seems to be all about HTML5 microdata, especially
because of Rich Snippets and Google's support for this approach.

http://html5doctor.com/microdata/#microdata-action

All three approaches allow you to embed iCalendar formatted event
information on a web page. All three of them do it differently. I'm
even more confused now than I was 5 years ago. This should not be this
hard, yet there is still no definitive way to deploy this information
and preserve the semantics of the event information. Part of this may
be because the iCalendar format, although widely used, is itself
insufficient.

Tom