Google’s core competency is organising information, so: search. They’re revenue comes from paid advertising from those wanting to reach the customers that come to Google for organised information.
Facebook’s core competency is organising people; so: social. They’re revenue is coming from paid advertising from those wanting to reach the customers that come to Facebook for organised social-life.
Apple’s core competency is software. That’s what they do best. They are great at user-interface and no one does it better. We, the users, have to fit in to their (often brilliant) systems, and we’re happy. We pay Apple for that service. The opportunity for competition is to actually pay attention to the user and listen to what they want.
Facebooks advantage (as seen in this article)
Recent developments have seen:
Apple (Software developer) becoming Social with Ping – link
Facebook (Social organiser) becoming retailler – see link
Google trying to be social – see Buzz and Google Me
Google becoming software developer – see Chrome OS
The fact is the lines have blurred. However my advice is that Facebook continues to focus on organising people, Apple continues to focus on making great software, and Google continues to organise the worlds information.