I have been knowing BeanOS since 2006 when I was working in Mexico . And I have taken some time to read the BeanOS source code to learn to write an OS.
 
Although at the end I didn't totally understand the whole BeanOS , I was able to get the concept of how an OS is developed, and how to implement a memory manager , how a booting process is ? and how to write a simple boot loader.
 
There are still more code to be explored, it is quite pity that this project seems abandoned.