Q:

How to add event to iCal / Outlook / gmail from webpage? 

include a link to download an .ics / .iCal file?   attach .ics file through email? 
How to construct the file?   Where to find the spec? 
What're the benefits of rendering the data in hCalendar on the page?   So search engine can index it somehow? 
Thanks

A:

There seems to be plenty of hits for the first part of your question on Google.   Also try CFLIB.org search and you can see how the function creates the text string
http://www.google.co.uk/search?q=iCal+and+ColdFusion
To download, write out the string to the browser using CFCONTENT.   To attach to an email, write out the string to a temporary file and you can use CFMAILPARAM to attach it.   Those are a couple of ways.