I don't have any ads in mine, although I do have ads in my Google Gmail. In looking at this more, it simply appears to be a way to convert a calendar into an XML feed that you can use on ANY calendar-type program and import the XML feed into your application to view it.
It appears that while Google says ANYONE can view it, what they mean is anyone can get the XML file of the calendar (the raw info). They do not support a HTML interface (something to see it on a standard Web page), for some reason.
So... I'm looking at a php script that takes the XML and converts it into something anyone can see. Any of you programmers out there with php knowledge that wants to work on this, please let me know.