Ngmoco’s chief publishing officer Simon Jeffery has resigned. According to GamesIndustry International, Jeffery is not moving to another company, but will instead work as a consultant and advisor to developers working on mobile-social apps.

Jeffery’s departure is the second high profile loss for Ngmoco this year. In February Ngmoco’s vice president of social applications Jason Oberfest left the company to co-found a mobile health startup called Mango Health.

Jeffery joined Ngmoco in June 2009 to oversee the company’s Plus+ publishing arm. In 2010 Japanese gaming giant DeNA purchased Ngmoco in a deal worth up to $403 million as part of its plan to bring its successful Mobage mobile-social network to North America. As we pointed out last month, with the passing of Ngmoco’s first earnout date, its not unexpected to see movement from within the company’s ranks. Jeffery’s departure is a significant loss for the company, however.

During Jeffery’s tenure as chief publishing officer, Ngmoco brought some of the most successful developers on iOS under the umbrella of DeNA’s North American Mobage network. Under his watch the company inked deals with Glu Mobile, TinyCo, NimbleBit, BackFlip Studios, Game Insight, The Playforge, Uken Games and RockYou among others. Ngmoco has not announced a replacement yet.

Prior to joining Ngmoco, Jeffery served for four years as the president and COO of Sega of America and for six years as the President of LucasArts.

Jeffery’s move marks the latest in a series of departures from DeNA’s North American ranks. In addition to Jeffery and Oberfest, Riz Virk and Mitch Liu left DeNA-owned Gameview Studios in early February.