If you needed any more proof that Zynga realises the importance of mobile to its future growth, witness chief mobile officer David Ko’s promotion this week to COO of the social games publisher.

“In his new role, he will oversee strategy planning, international, infrastructure and operations of the company,” CEO Mark Pincus wrote in an email to staff yesterday.

“Since joining us in 2010, we’ve all seen Dave scale our mobile organization, grow our portfolio by 25 new games and help unite game development teams on our cross platform efforts.”

The former Yahoo man’s promotion is part of a wider reshuffle, which sees another Zynga exec familiar to the mobile industry – former EAer Barry Cottle – moving from his current biz dev role to become chief revenue officer, focusing on “corporate and business development, distribution, strategic partnerships, advertising sales and operations, publishing and real money gaming”.

Also significant is the news that EVP of games Steve Chiang is now president of games, with responsibility for mobile and web, asked to “unite all of our game teams under one leader”.