After Google and Apple each acquired mobile ad networks in late 2009 and early 2010, the stage was set for the two tech giants to battle for dominance of the emerging mobile advertising landscape. An instant duopoly was born. When Apple launched its iAd platform in April, taking in a reported $60 million in upfront payments, it appeared ascendant in its duel with Google. But then came its stumble: actually working with agencies and advertisers on iAd executions, with some brands like Chanel dropping out because of the difficulty of working with Apple.

Among the raft of top 10 lists for 2010 Nielsen released today was a list of top paid app categories for the iPad. Not surprisingly, games was the most popular category, with 62% of users downloading game apps, followed by books (54%) and music (50%) -- and then shopping, and news and headlines, each downloaded by 45% of users.

Microsoft finally broke its silence on initial sales of Windows Phone 7 devices -- sort of. The company said today it has sold 1.5 million units worldwide in the first six weeks, but that figure reflects shipments to partners such as wireless operators and retailers, rather than direct sales to consumers.

On the heels of a Wall Street Journal report finding widespread privacy breaches on iPhone and Android apps, the Mobile Marketing Association said Monday it plans to develop a new set of privacy guidelines. The new rules would complement the MMA's existing Global Code of Conduct and cover eight types of mobile media: SMS, MMS, email, voice, applications, mobile Internet, content and location-based services.

Social networking has gotten its due from Time magazine, which this week named Facebook founder and CEO Mark Zuckerberg its Person of the Year for 2010 -- and "You" POY in 2006, in connection with the explosion of new forms of self-expression online through blogs and sites like YouTube. But what about the mobile space?

Smartphone penetration has hit nearly 30% in the U.S., according to Nielsen, up from less than 20% a year ago, as high-end devices become increasingly mainstream. But are the young users often prized by marketers part of the smartphone surge -- or are they sticking with regular cell phones?

The average amount of time spent per day on mobile devices has grown faster in the last two years than time spent using any other medium, according to new research findings from eMarketer. The 32-minute average in 2008 has increased more than 50% to 50 minutes in 2010 -- equal the average time spent reading newspapers and magazines, combined.

The super-hot local deals space just got more crowded with Visa introducing a new iPhone app with offers from more than 50 partners including Papa John's Pizza, Holiday Inn, Tourneau and Pearle Vision. Through the free app, Visa will show users nearby locations of participating merchants where offers can be redeemed.

Research firm IDC released a forecast today predicting revenue from mobile apps will hit $35 billion in 2014, driven by the exploding number of downloads -- from almost 11 billion this year to nearly 77 billion worldwide in 2014. IDC didn't release the full study and the release didn't break out the $35 billion figure by direct sales versus third-party advertising. But presumably the bulk of that amount will come from m-commerce rather than in-app advertising. Prices for paid apps are going up generally, and tablet devices will allow developers to charge more for titles.

Sprint and AT&T this week underscored their differing strategies on mobile data pricing, with Sprint sticking to offering an unlimited plan even as AT&T, Verizon Wireless and T-Mobile have switched to tiered-pricing based on usage.