In a new post to his site Paul Jones shares some of his thoughts about microframeworks, suggesting they're more "user interface" frameworks. Basically he suggests that microframeworks work best for the UI level handling and that possibly a second, more robust framework should be used for the application backend.
When we talk about “full stack” frameworks, we mean something that incorporates tools for every part of a server-side application. [...] Examples in PHP include Cake, CodeIgniter, Fuel, Kohana, Laravel, Opulence, Symfony, Yii, Zend Framework, and too many others to count.
When we talk about “micro” frameworks, we mean something that concentrates primarily on the request-handling and response-building parts of a server-side application, and leaves everything else out. [...] If the user interface is the request (as input), and the response (as output), that means micro-frameworks are not so much “micro” frameworks, as they are “user interface” frameworks.
He suggests that, if these statements are true, then microframeworks should be considered "user interface" frameworks. He makes suggestions of splitting things out into "containers" of functionality with the microframework taking care of user interactions while a second handles domain and infrastructure concerns.