The hamburger icon/menu introduces a metaphor of its own that is not consistent with progressive disclosure as used elsewhere in common interfaces (see above). It's more a "and here is the rest that you may be missing"-icon that isn't motivated by any consistent notion of the interface, but by concern for screen real estate. As a user, we may not assume the content of the menu, but by empirical knowledge and by considering functions that we are missing and that may be hidden somewhere.
The hamburger menu _is_ the application. It's content may be related to only by expectation and assumptions regarding the extent of the application's basic functionality. Arguably, in the light of this considerations, the icon is communicating rather sparsely what it is and what it does. (Actually, it exposes a global, unrelated view on the basic extent of the app.)
While its use may be arguable for an application (esp. mobile apps), it's highly problematic, when used in web sites and web applications. (The difference: While in the former case it's located rather in the window chrome, thus relating to the viewport as an object, it's part of the view in the latter – like a wormhole to the global context.)