Topic: Creating a 'subscribe to calendar' function

I've built my events calendar, all is functioning smoothly, and looking great.  I've even created an RSS feed for the upcoming events.

However... is it possible to create a resource that would allow me to subscribe to the events in either Google Calendar or iCal?  I presume so - aren't these built on XML standards?

Any help with this would be greatly appreciated!

Kind regards,
Ian