The iPhone keeps playing its siren song. And video game executives are falling for it.

Ngmoco, a high-profile iPhone game startup, is announcing today that it’s lured a top Sega of America executive as its new chief publishing officer. Simon Jeffery, president of Sega of America, said in an interview that he will join San Francisco-based Ngmoco starting today.

“The iPhone is a tremendously exciting once in a lifetime opportunity,” Jeffery said.

The move shows the iPhone is perhaps more iconic than Sega’s Sonic the Hedgehog now. It’s one of the biggest proof points yet that traditional video game talent sees the excitement building around the iPhone and is moving to get a piece of the action. Ngmoco itself was founded by Neil Young, a former executive at Electronic Arts, just a year ago. His cofounder, Joe Keene, said that Jeffery’s 22 years of expertise in games will serve him well as he undertakes big projects for Ngmoco.

Other iPhone/social game developers such as Zynga and Social Gaming Network have also recruited former executives from big game companies such as Electronic Arts. Keith Lee, founder of iPhone app maker Booyah, also leads a team of former World of Warcraft game developers, who are now making cause-related entertainment software on the iPhone.

The iPhone and the iPod Touch have sold more than 40 million units in less than two years. There are now 56,390 apps for the iPhone, including 11,985 games, according to Mobclix. Apple recently announced it has sold more than a billion apps through its AppStore.

Likewise, Ngmoco is growing fast and is living an accelerated life. It raised $5 million just after its founding in June 2008 and another $10 million in March. Its investors include Kleiner Perkins Caufield & Byers, Norwest Venture Partners and Maples Investments. The company now has 30 employees. So far, seven of Ngmoco’s games have appeared in the top 25 iPhone game ranks, Young said in an interview.

On Monday, Ngmoco launched Star Defense, its ninth game. Its a sci-fi title where you defend planets against attackers. Young said three more games are releasing in the next six weeks and 15 more are in development.

There is some theory out there that the big video game companies are going to come in and squash the little guys like Ngmoco. That may happen. Electronic Arts is publishing dozens of games on the iPhone, including the Sims 3, which debuted last week at No. 1. But Jeffery, who was at a big game publisher that was making iPhone games, clearly sees more opportunity at Ngmoco. And Keene noted that even the mighty EA can’t easily conquer this market. The Sims 3 has already been supplanted at No. 1 by an indie app dubbed Sally’s Spa.

I’ve interviewed Jeffery a number of times, both when he headed George Lucas’ game studio LucasArts and when he was president of Sega of America. He always prided himself on scouting out top game development talent to make games for the Western markets.

Jeffery’s job will be to head a new publishing group within Ngmoco and work with developers to get them to make games that Ngmoco will publish on the iPhone. While many iPhone developers are still run by their home-grown talent, Jeffery said he believes game publishing skills can directly transfer from big game companies to the iPhone game companies.

“Publishing is publishing,” said Jeffery. “I’ll be working with many of the same people that I already know.”

If he’s right, and if the iPhone game market keeps growing like it has been, you can expect to see a lot more defections from the old game companies to the new.