Zooko’s Triangle argues that names cannot be global, secure, and memorable, all at the same time. Domain names are an example: they are global, and memorable, but as the rapid rise of phishing demonstrates, they are not secure.
Though no single name can have all three properties, the petname system does indeed embody all three properties. Informal experiments with petname-like systems suggest that petnames can be both intuitive and effective. Experimental implementations already exist for simple extensions to existing browsers that could alleviate (possibly dramatically) the problems with phishing. As phishers gain sophistication, it seems compelling to experiment with petname systems as part of the solution.