The Arduino is a flexible platform with great ability to interface to most anything. It is a great platform to learn first and perfect for many smaller projects. The Raspberry Pi is good for projects that require a display or network connectivity. It has incredible price/performance capabilities.

The BeagleBone is a great combination of some of the interfacing flexibility of the Arduino with the fast processor and full Linux environment of the Raspberry Pi (more so in fact). 

An important moment in the history of tech, if you ask me.

This feels like recombination.