Moore's Law for software?

Had lunch with Joel Brinkley of Stanford University and talked about the idea of how the half life of a software firm's public awareness seems to shorten by about half for each generation.

Joel suggested that it sounded like the Moore's Law for software. I kind of like the ring of it.

Observations:

• IBM dominated between 1960's-1980's (You don't get fired by buying IBM)
• Microsoft dominated between 1980's-1990's (The evil empire)
• Google dominated around 2000's (Google is working on that problem)
• Facebook dominates since 2005 (Facebook has 500+ million users and counting)

I wonder who will gain the top spot next and how long that would last.