Apple's Top Mac OS Executive To Depart

Serlet, who joined Apple in 1997 and is understood to be close to Apple CEO Steve Jobs, is senior vice president of Mac Software Engineering. Apple did not provide a specific reason for his departure, and in a statement, Serlet -- who worked at the Jobs-founded NeXT before its acquisition by Apple -- said he wanted another focus.

"I've worked with Steve for 22 years and have had an incredible time developing products at both NeXT and Apple, but at this point, I want to focus less on products and more on science," said Serlet in a statement.

According to Apple, Craig Federighi, vice president of Mac Software Engineering, will assume Serlet's role and report to Jobs. Federighi has been managing Apple's Mac OS software engineering efforts since his return to Apple from Ariba in 2009, and is also responsible for the development of Mac OS X.

"Craig has done a great job managing the Mac OS team for the past two years," Serlet added. "Lion is a great release and the transition should be seamless."

Apple's Jobs is currently on medical leave, his third leave of absence since being treated for pancreatic cancer in 2004 and receiving a liver transplant in 2009.

Apple COO Tim Cook is managing day-to-day operations at Apple in Jobs' absence, although Jobs did make an appearance in San Francisco earlier this month to introduce Apple's iPad 2.