U.S. mobile social media usage rose by 37 percent in the past year, with 72.2 million Americans accessing social networking sites or blogs via mobile device in August 2011, according to research by comScore, Inc.

Almost 40 million U.S. mobile users – over half of the estimated U.S. mobile social media audience – visit social media sites via mobile each day, reports the research firm.

comScore’s research also shows that, right now, more mobile users access social media sites via their mobile web browser than via a social networking app (42.3 million compared with 38.5 million).

This is likely to change, however. The growth in users accessing social media sites via social networking app is much higher than the growth in access via mobile browser. In the last year those accessing social media sites via mobile browser rose by 24 percent, compared with the huge 126 percent growth in the audience for social networking apps.

By 2013, social network advertising revenues will reach $10 billion worldwide, up from $5.54 billion this year, according to eMarketer. Facebook is set to grab the lion’s share of those revenues, with Facebook’s ad sales expected to climb from $3.8 billion this year to $7 billion in 2013 (70 percent of the total).

Twitter’s ad sales are expected to rise from $139.5 million in 2011 to $399.5 million in 2013. LinkedIn will also see impressive ad revenue gains. eMarketer expects LinkedIn’s ad sales to grow from $140.8 million this year to $249.6 million in 2013.

More people are ‘Liking’ or sharing shopping items or links with their social media followers than forwarding them to friends via email, recent research shows.

A Responsys study of top online retailers finds that their use of ‘email-to-a-friend’ or ‘forward-to-a-friend’ via email has declined 15 percent since 2009, while the use of buttons and links enabling consumers to share with their social media network has increased by 12 percent.

The number of mobile social network users is expected to grow from 1.1 billion worldwide in 2011 to 1.9 billion by 2016, representing a cumulative annual growth rate of 11.8 percent over the next 5 years.

Based on research from Visiongain, the outlook for mobile social networking is positive as market players and users alike experience changes in monetization models, fervent competition between vendors, and localization trends.

Food and beverage companies are failing to optimize their social media marketing efforts, according to a recent study. Over half (54 percent) of food and drink industry professionals admit they don’t measure the return on investment (ROI) on their social media marketing investments.

According to the survey of over 500 food and beverage executives by U.K. based just-food and just-drinks, a further 18 percent ‘did not know’ if their business measured the ROI.

A recent study of 12 million employees at U.S. companies reveals the most social media-savvy companies, industries, jobs and cities in terms of Twitter, Facebook, and LinkedIn usage.

According to the 2011 study by NetProspex (http://www.netprospex.com/np/social), the most social company is The New York Times, followed by Intuit and Juniper Networks.

U.S. pop artist Lady Gaga (a.k.a. Stefani Joanne Angelina Germanotta), holds the Guinness World Record for the most Twitter followers. As of June 29, 2011, her @ladygaga Twitter account had 11,259,372 Twitter followers.

Lady Gaga was the first Twitter account holder to exceed 10 million followers (on May 15, 2011). Canadian singer Justin Bieber had the second biggest Twitter following, with 10,646,695 followers, on June 29, 2011.

Twitter users are now sending 200 million Tweets per day, according to Twitter. That’s quite a jump from the average of 2 million Tweets per day observed in January 2009, and the 65 million per day noted just a year ago in June 2010.

According to Twitter, the most popular trending topics for the first half of 2011 were as follows:

Where do U.S. hotels, bed and breakfasts (B & Bs) and innkeepers spend most of their marketing budgets these days? If you’re involved in the travel industry – or have recently researched or booked travel – you’ll know the answer: on the Internet!

Of the three biggest marketing expenses among accommodation businesses, the biggest expense is online advertising and the third is online travel agency commissions.

May 2011 research from InboxQ indicates that Twitter users want businesses to respond to them when they have questions, complaints or comments about those businesses.

Interestingly, such Twitter users don’t necessarily direct their Tweets to a given company with a @ reply or direct message. Instead, they’ll send the Tweet to all their followers. Yet, according to InboxQ, more than half (58 percent) of Twitter users still want the business to respond to them.