Russell Buckley, AdMob’s first employee (after founder Omar Hamoui) is leaving Google after almost five years with AdMob and, subsequently Google.

Buckley joined AdMob in 2006 and was a regular on the conference circuit, not only pitching the mobile ad network’s services, but also moderating panels and speaking about wider mobile marketing industry issues. He has also served in several capacities with the Mobile Marketing Association, including as its global chair. On a personal level, there are few nicer, more unassuming people in the business.

Before joining AdMob, Buckley was known for his MobHappy blog, and his work at his start-up, ZagMe, which, among other things, targeted shoppers at the Bluewater shopping centre in Kent, UK, with location-based offers. In 2001.

He will leave Google at the end of March. Mobile Marketing understands from friends of Buckley that he plans to do some Angel investing and advisory board work, but is in no rush to get back into big corporate life. But it’s hard to imagine that he won’t be involved in the mobile scene in some capacity.