Yes - no content is ever sent by an HTTP GET AFAIK, except that passed in the URL and its query string (and possibly in custom HTTP headers, but let's no go there).
I thought I had put in a link to the Meetup API in that section.
When you are using the sample application you are using my credentials at the program level (and so is everybody else); for your own program you will want to create your own.

Glad you like it!