I'm an Australian, and I can assure you that kangaroos hop. In addition to the echidna being found in New Guinea, it is native to Australia - however we have the short-beaked type.

Your link to the NYT echidna article by Natalie Angier goes to their tiresome login.

I've found this link, which may be easier if it does not time out:

http://www.nytimes.com/2009/06/09/science/09angi.html?em