Here’s some more good information. Some may be “geeky” but you’ll see where things are going.
http://www.slideshare.net/grigs/native-vs-web-vs-hybrid-mobile-development-choices
There’s also a great use case based on numbers reported from Zillow’s CEO (Rich) and their iPhone app,which illustrates that it would take even them about 9 years to break-even on paid ads. Most people do not have 6 million+ visitors/mo and $80 million in VC funding. In the slides above,a company spent $32K on an app and yielded a whopping $535 return.
As noted,it serves more as a marketing/differentiation tool now for most. You hear about Google’s,Ebay’s,YouTube’s,etc. because their successes are rare. You don’t hear about the 95 failures,out of every 100 venture-backed businesses. The same phenomenon seems to hold true with the app craze. There are 40-50 (out of 140,000) that you hear stories about people getting rich,the rest – you guessed it. 
The best business case for apps is to solve a specific problem for an existing client base,like mobilize your current customers. With consumer-facing use cases wins are quite rare. Downloads don’t tell the whole story;it’s returning users,but you’ll see many companies don’t report that. Those Pinch Media studies monitored over 30 million downloads,free and paid,and you’ll see those steep drop off curves to nearly 1% repeat usage after 90 days.