In this recent post to his site, Phil Bennett shares some thoughts about the PHP-FIG, the standards they're proposing and how the shares interfaces might help reduce dependencies in framework-based applications.

[Frameworks] come in several different flavours that all have huge advantages, but also a few disadvantages. Over engineered (because their popularity demands that they be), updated too often, not updated enough. If you decide for example to update your application from using Zend Framework 1 to using Zend Framework 2, this will more than likely require, at least in part, a re-write of your code. This makes scalability difficult.

He talks some about the PSRs that the PHP-FIG group has proposed including the PSR-3 logging interface structure. He points out that, by having this same structure, it makes injecting dependencies easy while still leaving the actual functionality open to interpretation. He also suggests that maybe a framework isn't the right choice for all applications and that possibly using a collection of libraries, tied together by the PSR standards, could be a better answer.