Look for new enabling technologies that create a wide gap between how things have been done and how they can be done.

I believe there's plenty of market for each; we're talking about an ecosystem that is going to support billions of devices, so a competitive landscape is good for consumers, developers, and the platforms alike. Apple brings a smooth elegance to its devices and platform, with the best marketplace experience to boot. Google brings a higher volume of devices as well as a more diverse ecosystem to interact with. The real story here is that Microsoft is nowhere to be seen, ending a two-decade monopoly and creating biggest opportunity for software startups probably ever.

If you're in your early 20s and you're hanging out with a bunch of other people in their early 20s, nobody has a sense of the kinds of problems that real 'workers' run into every day. They're running into a completely different set of problems like 'what's the party going on right now that I should be going to?

Any time where the delta b/w what is possible and how things work today is at its widest, that's an opportunity to go build new technology.

What happens to the Microsofts, Oracles and IBMs of the world is that when they get big enough, they don't think they need to bring that same level of focus and energy to the end-user experience.

Always look for these changing technology factors- any market that has a significant change in the underlying raw materials ...or enabling factors, is an environment that is about to change in a very significant way.

Tip: Take the stodgiest, oldest, slowest moving industry you can find. And build amazing software for it.