Sheryl Sandberg, chief operating officer of Facebook, said this week that mobile is as important, if not more important, to marketers than television. While many in the advertising world would agree with Ms. Sandberg, others are not so sure mobile has reached its full potential yet or that it will ever replace TV entirely.

Speaking at an event in London this week, Ms. Sandberg said that the size of the mobile phone audience makes it a mass medium with significant importance for marketers. The statement was made at a time when Facebook is looking to significantly ramp up its mobile advertising business as its user based continues to migrate to smartphones.

?I wholeheartedly agree with Ms. Sandberg?s statement,? said Craig Elimeliah, vice president and director of technology and digital solutions at Rapp, New York.

?Mobile is context, it is the new fabric of our beings and how we navigate the world today,? he said. ?TV has been struggling to keep its head above water and even the TV that is working is competing with so many other screens that anything done on that platform is diluted simply because of the distractions that are all around us.

?Mobile advertising is going to be an extremely hard nut to crack and we may need to rethink advertising completely but that is what makes it so exciting.?

The second screen
Smartphone penetration in the United States reached 57 percent earlier this year, according to comScore, meaning there are already a significant number of Americans marketers that can potentially reach consumers via mobile phones. Adoption levels have not stopped growing, either.

While mobile is often called the second screen, in reality users are carrying their mobile phones with them everywhere they go throughout the day, using them to consume snippets of content along the way. As a result, many users are spending more time with a mobile screen than they do on traditional media.

However, it is not just mobile?s always-on nature that is attractive to marketers. There is also the fact that consumers are increasingly using their mobile phones for shopping-related activities and to engage with social media outlets, opening up brand new, still-to-be-explored opportunities for leveraging mobile.

To date, marketers have been slow to respond to the significant growth in mobile, but this is starting to change. The Interactive Advertising Bureau reported yesterday that mobile accounted for nine percent of the overall ad spend on digital advertising last year and expects this number to continue to grow.

Some marketers have caught on to mobile?s potential and are already putting significant emphasis on it.

?The most interesting stuff happening right now is integrating gaming, television and mobile all together,? said Joakim Borgstrom, a director of innovation at Goodby Silverstein & Partners, San Francisco. 

?'Walking Dead' is doing a killer job of this,? he said. ?The upcoming SYFY-channel show 'Defiance' also lets multiplayer gaming affect the show's plot line.?

A part of life
However, much of mobile?s potential as an advertising medium is still to be realized, with slow-moving marketers only partially responsible for the hold up.

Mobile also presents several challenges that still need to be overcome.

For example, many would argue that the best way to deliver mobile ads has yet to be determined. Mobile is still a relatively young medium and marketers are struggling to figure out how to engage consumers here.

?Mobile can't be about interrupting people with iAds, we need to give people something they care about, something that makes their day better,? said Niklas Lilja, a director of innovation at Goodby Silverstein & Partners.

?Done right, mobile gives marketers a unique shot at becoming a part of people's lives - and for a fraction of the cost of a TV campaign,? he said.

Accurate measurements
Another challenge is the relative dearth of methods for accurately measuring the effectiveness of mobile ad campaigns in part because of difficulties associated with tracking the behavior of mobile users.

Many marketers are reluctant to allocate bigger budgets to mobile until the measurement issue has been resolved.

?When clarity and consistency to mobile campaign measurement is set in the near future, I strongly believe that this on-the-go medium will be one of the most important medium to marketers,? said Angelina Chung, group digital media director at G2 Worldwide, New York.

?In the future, mobile medium has potential to surpass TV as mobile/tablet can be ?TV? and most importantly, the beauty of mobile is that eventually sales can be measured through the devices which can be factored into the overall ROI,? she said.

If measurement data comes to smartTV sooner than mobile, this could be a game-changer, per Ms. Chung. However, penetration for smartTV is still very low.

In the mean time, some marketers are finding mobile and TV work well together.

?Marketers are seeing that mobile advertising works very well with other medium such as TV as part of more integrated campaign approach,? Ms. Chung said. ?Consumers are no longer sitting on their couch watching television, but they are multitasking more than ever, either using their smartphones or tablets.?

Leveraging social media
Marketers also need to learn how to leverage existing social media platforms as well as newer ones to engage with mobile users as social becomes pervasive throughout the mobile experience.

Social media platforms such as Vine, Pinterest and Instagram have seen significant growth in consumer use and marketers are eyeing the opportunities to reach these users.

?I see non-linear platforms like Vine, Pinterest and Instagram as ideal platforms for mobile advertising in a very native and unobtrusive way,? Rapp's Mr. Elimeliah said. ?They embody the core elements of what makes mobile mobile and are uniquely designed to accommodate all kinds of communication from brand advertising to deep story telling.

?We are on the cusp of a completely redefined ad industry, going from three channels to literally hundreds of channels in no time at all shifting the tectonic plates that this industry has sat on for a century,? he said.

However, some would argue that mobile is still an immature advertising medium and will remain an ancillary tactic until many of these issue are addressed.

In the mean time, marketers should not view TV and mobile as in competition with one another.

?No, I don't think mobile is more important than TV advertising and I don't see TV advertising as more important than mobile, because I don't see them as in 'competition' with each other but rather different, complementary tools that should be used to achieve different goals - and very often in conjunction with each other,? said Andy Wasef, head of innovation and technology at MEC.

?Our goal for mobile marketing and advertising should be to establish its best application for different goals for communicating with, and engaging, people,? he said. ?Until we do that, we'll remain an immature option for marketers and remain a sidekick to other options.

?Once we refine those mobile tools for brand marketers, including the right forms of mobile advertising, as well as robust audience measurement and ROI measurement, then it'll rightly be viewed as a crucial part of our tool box - throughout an organization?s value chain and not just marketing.?

Final Take
Chantal Tode is associate editor on Mobile Marketer, New York