A new study claims that nearly 30 million mobile subscribers worldwide may use mobile social networking services by 2012.

The study, from In-Stat, said that Millennials, otherwise known as Generation Y, will be among the key demographic drivers of this mobile social networking trend.

Per the report, titled "Mobile Social Networking: Marketing to Millennials," blogging, photo and video sharing, games, SMS text messaging, instant messaging and location-based socialization services will all mesh into the social networking experience from a mobile phone.

The introduction last year of the Internet-enabled and user-friendly Apple iPhone has changed user expectations of the mobile phone.

However, the key challenge in the online space afflicts social networking in mobile too: how should social networks and application developers generate revenue from their services?

Advertising, subscription services and premium upgrades are the three sources of revenue for mobile social network applications.

Social network advertising remains an experiment for marketers, although revenue this year is estimated at $1.5 billion, according to In-Stat, Scottsdale, AZ.

In-Stat wireless industry analyst Jill Meyers takes questions from Mobile Marketer's Mickey Alam Khan on Millennials' attitudes, advertising on mobile social networks and the revenue potential. Here's the interview:

What's the charm of mobile social networking to millennials?
More than half of millennials have a cell phone and mobile social networking allows them to update their profiles, post pictures and announce events to the world without having to go home and log on to their personal computer.

It is fast and easy and it allows real-time communication to an entire group of friends.

What repercussions will this have for advertising?
I think this really opens up a whole new market for advertisers. Cell phones are always on and always with their owners. People will walk out of the house without their wallet, but turn around to go get their cell phone. So, cell phones pose a unique opportunity to reach potential customers.

Moreover, the personal data associated with the cell phone operators as well as the social networking sites allows for very specific target marketing opportunities.

Where this leaves the mobile operators and social network site operators is with a wealth of very valuable data and a very fine line regarding the privacy of their subscribers.

How will mobile social networks generate revenue from this trend?
There is the million-dollar question. The personal data submitted to mobile social networking sites is valuable to advertisers, and there is a huge potential for advertising dollars for specific target markets.
These data include not only the basic demographics, but the posts the members make as well.

For example, if members post that they went to see the movie "Iron Man," the social networking operators could potentially market that group of members to the marketers for "Incredible Hulk" (see story).

The trade-off is for the social networking operators to find a way to segment their users in such a way as to provide a targeted demographic, without alienating their members.

Advice to advertisers and marketers?
Cell phones and social networking sites are very both personal. I believe the messages need to be relevant. Just because the medium is there, doesn't mean that it is appropriate for every product.

Just like with all advertising, I think my advice would be know your market and then decide if this is the right medium for your product.

Mobile advertising is in its infancy right now -- mostly limited to text messages or banner ads on WAP pages. I think that, in time, it will become sophisticated and timely, if customers don't get tired and turned off before it matures.