Here’s a somewhat arbitrary listing of stats about current and future mobile marketing and smartphone use. I’ll add links and citations, and more stats, as I can. (If you would like to add a source, please do so in the comments.)

Worldwide sales of smart phones are expected to reach a staggering 1.1BN in 2015, according to a recent report by Gartner. As early as the end of 2011 it is expected that smartphone sales will be 468 Million units, a 57.7% increase on last year.  This growth should continue over the medium term culminating in 1.1 billion units expected to be sold in 2015.

Smartphone sales have surpassed PC sales, worldwide. According to PC Magazine, “vendors shipped 100.9 million smartphones during the fourth quarter, according to Monday data, while IDC logged 92.1 million PC shipments during the same time period, according to IDC numbers from January.”

Android is expected to consolidate the dominance they set in the market at the end of 2010, growing their current 23% market share to an authoritative 49% in 2015. “As vendors delivering Android-based devices continue to fight for market share, price will decrease to further benefit consumers” said Roberta Cozza, principal analyst at Gartner.  “Android’s position at the high end of the market will remain strong, but its greatest volume opportunity in the longer term will be in the mid- to low-cost smartphones, above all in emerging markets.”

74% of iTunes App Store proceeds are from in-app sales. (Citation needed.)

Meanwhile iOS are expected to remain the second biggest platform worldwide through 2014. (Gartner)

A variety of global app download reports are available here: http://xyologic.com/app-downloads-reports

Super-blogger John Chow says that the Spanish speaking market now has the largest potential for growth. (Sorry, no citation available yet.)

BloomWorlds BloomBlog reports that the average smartphone user is considerably wealthier than the average adult. Smartphone users have an average household income of $66,000. In contrast, the average household income is $44,000, meaning smartphone users are on average 50% wealthier than the general population. Smartphone users are more than 2 times as likely as the average mobile subscriber to make more than $100,000/year.

According to Mobile Entertainment:

• The average paid iPhone app has sold 101,024 copies over a lifetime of 261 days
• US iPhone users download 60 apps a year
• 51% of iPhone owners have five or more games installed on their devices says Compete
• 37% of iPhone owners play games at least every day – puzzle games are most popular

Business Insider says global app downloads for year-end 2011 are expected to balloon to 29 billion, compared to only nine billion in 2010. Such stellar increases are largely due to the proliferation of smartphones around the world. The total smartphone install base is expected to grow 46% in 2011.

Kevin Miller, writing for Developer Tech:

“The hype that surrounded Apple’s announcement about the iPhone 4S reflects not only the interest in Smartphone’s but also the demand for apps.  In a little more than 3 years, more than 18 billion apps have been downloaded from the App Store and that number currently stands at over a billion a month. This number excludes other platforms such as Android.

“The app market is one of the few sectors that remain unaffected by the current economic climate and this is drawing in more and more business people who want to channel their creativity so as to improve productivity and profitability within their organisation.

“With the app market expected to reach $25 billion by 2015, how can UK SME’s and other businesses tap into the App revolution to fuel their growth?”