It is evident brands are realizing the benefit of mobile since campaigns sending traffic to site as a landing page increased 10.46 percent in June.

This is one of the key findings in Millennial Media's Smart report for June. The study also found that the average monthly page views per user was 99 page views in June.

"There were some key maturational indicators in the second quarter," said Mack McKelvey, vice president of marketing at Millennial Media, Baltimore, MD. "The early movers in mobile, namely entertainment and auto, continue to invest in their mobile strategies.

"Entertainment advertisers, particularly movie studios, stand out as a best practice in numerous ways -- studios masterfully target -- audience, demo, takeovers," she said. "They know the power of the mobile ad network model and they strategically leverage it to target and engage their consumers with unique interactions at various points in their campaigns.

"We've seen an insurgence of other categories this year and in second quarter carriers and device manufacturers aggressively leveraged mobile, as did major portals. Traditional advertisers are utilizing mobile as a strategic channel to engage their consumers."

The United States' mobile Internet reach has increased to 59.8 million users and Millennial Media reaches 74 percent of the mobile Web, or 44.2 million users, according to Nielsen.

According to Millennial's research the top 10 mobile ad verticals in the second quarter were entertainment, telecommunications and portals, respectively.

Entertainment knows mobile. Movie studios, in particular, have leveraged the mobile ad network model to reach, target and engage consumers.

Movie studios also deliver rich brand experiences on their persistent mobile sites, yet creatively leverage custom landing pages and rich media at different stages of the campaign lifecycle, according to the study.

"There was validation in this study," Ms. McKelvey said. "Validation through consistent data that that the mobile internet is growing a sustainable rate, mobile is measurable and real.

"Traditional advertisers are ramping up their mobile strategies," she said. "The network model is providing real value at real scale."

Monthly CPEU rates remained consistent in the second quarter across multiple campaign targeting methods, as did percentage changes among the campaign targeting mix.

In fact, 48 percent of campaigns used frequency capping in June.

Millennial's study also found that average session time increased significantly from 4:28 to 5:38 in the second quarter.

However, 98 percent of page views featured only one ad request in June.

Of one thing there is no doubt: The iPhone is making history.

Sixty-eight percent of impressions on Millennial Media's network in June were from iPhone and iPod touch devices.

Apple's impression share increased 4.20 percent in June. However, Samsung remained in the No. 1 position with the largest impression share throughout the quarter.

The iPhone regained the No. 1 spot - this also contributed to the 1.4 percent month-over-month growth of Touch Screen device share versus other input mechanisms.

The Blackberry Curve and Blackberry Pearl remained consistently in the No. 3 and No. 5 spots respectively month over month -- while T-Mobile's HTC G1 (Dream) took the No. 7 slot in June.

"More smartphones and feature phones in the market will lead to more addressable audiences, broader reach and increased opportunities for brands to reach their consumers," Ms. McKelvey said. "It goes back to the point of maturation.

"In this area, mobile resembles the early days of online. Brands are starting to invest in their persistent mobile sites to ensure consumers are able to interact with their brands in a mobile environment," she said. "Persistent mobile sites pave the way for mobile CRM and mobile commerce.

"These are extremely positive indicators for the overall mobile ecosystem."