Please explain Arduino 1.5 Library folders

I apologize if this is covered elsewhere but I am seeking a simple explanation of the Arduino 1.5 IDE in regards to the library folders.
In 1.05, there was 1 common library folder which I understood.
In 1.5 it seems there is still a Library folder in \Arduino\Libraries but there is also a Library folder for each variant, example Arduino\Hardware\Arduino\Rfduino etc.

Does this mean that if you have a library like Adafruit_GFX you have to install that for every platform that you intend to use?
I just installed the latest 1.5 Beta and when I try to import Adafruit_GFX, it says the library already exists.
After doing a search I see that this library is included in the folder Arduino\Libraries\Robot_Control\SRC\Utility.
However when I try to compile my sketch which includes #include <Adafruit_GFX.h>, it says no such file or directory.

This is very confusing as it seems I cannot install a library because it exists "somewhere" but not in a place that the compiler can find.
The only reason I am even bothering with this is that i am trying the RFduino which will only use 1.5.

Any help appreciated.

Thanks

Well I guess I found some information myself. From what i understand is that when you #include a library, the compiler will first look in your sketch/Libraries folder, then will look in the arduino/Libraries folder and failing that will look in the platform/libraries folder.
While I understand this may look neater and be easier for the library writers to write something specific to their product, my experience is that libraries are subtly adapted by even non-pros like myself to fit a particular application. It was easy to keep track of when they were all in one folder. I think this will make it very difficult for the weekend hackers to find and install libraries and makes Arduino not so easy and friendly anymore just to accommodate higher end processors. If Teensy can do use high-end processors and keep it simple then so should Arduino.