Software:
Judging by the fact that most of Facebook is based on PHP, it sounds to me like it's pretty robust... It's also object oriented.
And functional
The only drawback that I would find as a code-geek is weak typing
Which Facebook is addressing with their language Hack, which is heavily based on the PHP language. As a bonus, you also get a language that's built from the ground-up to be fully functional with their HHVM technology. It's an exciting time for PHP.
Android is free and open
So where's the Raspberry Pi distribution (that actually works) if it's so free and open?
I tell them to turn to the study of mathematics, for it is only there that they might escape the lusts of the flesh. -- Thomas Mann, "The Magic Mountain"