There's plenty going on in terms of investment money flowing into iPhone's social networking platforms.

The most recent, and significant, deal was the 20 percent stake of Aurora Feint - the developer of OpenFeint - acquired by Japanese mobile social operator DeNa.

Full terms weren't revealed, other than it was worth multi-millions of dollars, and that DeNA might increase its stake "if warranted", as the company looks to expand into the North American and European iPhone and smartphone markets.

And considering the size of DeNA - its predicted income for its current financial year is £287 ($478) million, with a predicted net income of £57 ($94) million - it's certainly got the muscle to fast track OpenFeint's development in terms of features such as multiplayer and in-app commerce.

We caught up with Shinichi Ikeji, DeNA's US marketing director to find out some more about the thinking behind the deal.

Pocket Gamer: Why is DeNA interested in social networking on iPhone?

Shinichi Ikeji: DeNA is a leading mobile social network company in Japan where the largescale traffic shift from PC to mobile internet happened several years ago. The same trend is beginning in the US and European market, driven by the iPhone. Once you find out an attractive market where your expertise is useful, why not enter it?

Why did you decide to invest in OpenFeint rather than just using the technology?

Rather than joining OpenFeint network as a publisher, DeNA wants to be involved in developing social gaming platforms with Aurora Feint and OpenFeint. We strongly believe our experience in developing and operating social network service communities with high user engagement will be beneficial for both iPhone game developers and players.

How do you think your experience in the Japanese mobile market will see the OpenFeint technology mature?

OpenFeint is already a successful social gaming platform on iPhone. However DeNA's know-how in terms of developing active social network service communities, handling large mobile traffic (over 700 million daily pageviews), and monetisation will help OpenFeint to go step further.

Specifically, how important do you think e-commerce will become for iPhone games?

Successful Asian services including DeNA's Mobage-town have proved that the free-of-charge with pay-if-you-want-to business model brings larger revenue than the download payment or monthly subscription model. Iphone is apparently heading towards the same direction and we have no doubt this trend will become major revenue source for iPhone games.

Conversely, how important do you think that Aurora Feint and OpenFeint will be in helping DeNA break into the US and European markets?

Very important. We have made up our mind to develop the global smartphone market with Aurora Feint and OpenFeint. An excellent team is a must for us to execute our strategy. From that perspective, the Aurora Feint and OpenFeint team has already exceeded our expectation. It is very motivated and energetic. Also its sincere attitude to listen to game developer community is impressive.

Thanks to Shin for his time.

You can follow DeNA via its website.