I don't think that he's asking a question, but instead he's giving an example on how to get invisible traffic, in which in the form of putting your URL in an image.
Hi all, I think cheating on Alexa's ranking (or Google's PR or other stuffs out there) might be even more difficult than increase your Alexa Ranking (using SEM, SEO, Affiliate Network, NL, Social Networks, etc. etc. etc.); so why would you bother?