In a potential blow for the open source Android mobile operating system, engineering director Steve Horowitz is leaving to become CTO of Coupons Inc.

Horowitz led the team that built the Linux-based Android operating system and platform, which was launched with the T-Mobile G1 last year. He will oversee the worldwide engineering, product management, and technology efforts of Coupons, which owns properties like Coupons.com and the Digital FSI network.

"Our business is experiencing unprecedented growth, and as we extend our digital promotions platform to in-store, in-appliance, and mobile phones, this is the ideal time for Steve to bring his deep experience to our team," said Steven Boal, CEO of Coupons, in a statement. "Steve is a business-minded, consumer-focused, and battle-tested technology leader, and I couldn't be more thrilled that he is joining our team."

Horowitz began his career at Apple and worked on the first extensible Macintosh Control Panel. Before working with Google, he spent nearly nine years at Microsoft working on products like IPTV, Windows Media Center Edition, and WebTV.

"Coupons.com has fast become one of the world's leading online brands, so this is a very exciting opportunity," Horowitz said in a statement. "The company is at a pivotal point in its business, and I am eager to help further advance its development and deployment of new platforms and services for digital promotions."

Google had not responded to press inquiries by midday Wednesday about who would be filling the leadership void on the Android team. The open source operating system is scheduled to soon receive a "cupcake" update, which should add a virtual keyboard, stereo Bluetooth support, and improved Web browsing.

This year may be an important one for Google's mobile ambitions, as Samsung, Motorola, Sony Ericsson, and Garmin are expected to release Android-powered handsets. But the smartphone market will be increasingly competitive as Research In Motion, Windows Mobile, Palm, and Symbian will be launching new hardware as well.