Bruce Eckel uses the term latent interfaces to describe Python (or other dynamic languages') implicit interfaces (if it looks like a duck). I hadn't seen that term before, but I quite like it.
'Latent Typing' is also the subject of Bruce's keynote at PyCon in a few weeks --
http://dc2004reg.pycon.org/dc2004/talks/keynote
in this talk I will look at various issues and arguments surrounding the concept of type, and in particular examine the phenomenon of 'latent typing' (often called 'weak typing'), why the concept is powerful, and how it is expressed in different languages. In the process, I will attempt to clear up many of the issues that have arisen during attempts to describe Python's place in the spectrum of language features
...wish I was going to be there. Hope that he puts the text up on his website.
And does Bruce's novel term provide clarity or confusion?
What is the relationship between an explicit Java interface and a latent type?
What is the relationship between an explicit interface and an implicit interface?
http://www.jot.fm/issues/issue_2002_05/article1# Isaac Gouy