AT&T Interactive Chief Product Officer David Yoo resigned last Thursday, Nov. 12. He has been replaced by Spot Runner vet Will Hsu, who had been recruited by Yoo to AT&Ti.

Yoo came to AT&Ti from TellMe after helping sell that company to Microsoft for $850 Million. While at AT&Ti, Yoo led the relaunch of several mobile and online properties including Yellowpages.com, YP.com and the soon-to-be-relaunched buzz.com. He also led the company in its mobile and new ad strategy initiatives.

Yoo’s next steps aren’t known. Although personal reasons were cited, specifically an interest in returning to the Bay Area from Los Angeles, we’d speculate that Yoo plans to join a start-up sometime next year.