I am having this idea where modules and extensions are place in a single location, and they are shared among multiple Yii Application, so it would be easy to maintain them.
In that case I would define an alias that points to a central location inside my Yii Apps, and load them from there, customized views/settings will still be inside each Yii apps themselves.
What do you think?
The immediate issue that I can think of is for when you have to relocate your app from one server to another. This is where you have to manage symbolic links.
We put the main Yii framework in our PHP path, you could do something similar for what you mention. You would just need to make sure everyone maintains a common "lib" directory (or similar), which would work for your own developers but would be harder if you are distributing the app, in which case, you could use a build script to include the 3rd party libraries.