Smartphones continue to grow in popularity. According to Nielsen’s May survey of mobile consumers in the US, 38 percent now own smartphones.

At Nielsen’s Consumer 360 client event in Orlando Florida, Paul Swiontkowski and Kim Stanford from Microsoft shared how they efficiently delivered television ads to the viewers most likely to respond to Microsoft’s message.

With more consumers using smartphones and connected devices like the iPad, there is no avoiding the importance of mobile apps. Apps are responsible for 56 percent of all smartphone activity according to data shared by Jonathan Carson, CEO of Telecom at Nielsen, during Nielsen’s Consumer 360 conference.

Nielsen’s Jon Gibs discusses how viewers engage with social media and television and how it’s creating a new type of “co-viewing.”

Adam Lashinsky, Senior Editor at Large at Fortune Magazine moderated a panel discussion at Nielsen’s Consumer 360 with Mike Brennan, COO Peapod; Anne Jones, VP, Business Development, Kimberly-Clark and Steve Nave, SVP and GM, Walmart.com.

According to Nielsen’s monthly analysis, smartphone owners, especially those with iPhones and Android devices, are consuming more data than ever before on a per-user basis.

During May 2011, there were 145 million unique viewers of online video in the U.S. who streamed over 15 billion videos and averaged 4 hours, 20 minutes viewing video content over the course of the month.

According to a Q1 2011 survey, 39.2 percent of mobile consumers in Spain now have smartphones. Nokia’s Symbian operating system remains the most popular with 65 percent market share, despite a 9 point decline since Q4 2010.

A recent survey of the top 300 advertising agencies in Brazil, Argentina, and Mexico, which was undertaken by Nielsen on behalf of the Mobile Marketing Association (MMA) in Latin America, underlined the tremendous growth potential of mobile media in the region.

In the Cross-Platform Report, Nielsen finds a resounding trend: Americans are spending more time watching video content on traditional TVs, mobile devices and the Internet than ever before.