Apple announced on Wednesday that Bertrand Serlet, the software engineer instrumental in the development of Mac OS X, is leaving the company. Serlet, who said in his departure statement that he wants to "focus less on products and more on science," has worked with Steve Jobs for 22 years, and was the driving force behind the software that helped launch the company back into prominence in 1997. In recent years, Apple has focused on mobile devices, even modeling its new operating system, the as-yet-unreleased Lion, on iPhone software. Is Serlet's exit a clear sign that Apple is completely focused on handheld devices?

This looks like a new era: The diminishing role of Apple's desktop OS probably "played a big part on this decision," says Jesus Diaz at Gizmodo. It seems that Scott Forstall, a longtime employee who heads up Apple's iPhone operating system team, has replaced Serlet as the new "rising star." Even if Serlet is leaving simply becuase he's "tired," Apple is losing one of its "most brilliant minds" at a crucial moment in its history. "And that just doesn't feel good to me."

"The father of Mac OSX is leaving Apple"

Don't count out the old OS just yet: Yes, Lion signals Apple's unification of mobile and desktop operating systems, says Giles Turnbull at TIME. But the two platforms are "not one and the same, and quite possibly never will be." Even if desktop devices have "sleek touch-sensitive surfaces like their handheld cousins," they will still run on different operating systems. Serlet's exit may mark "the end of an era," but it doesn't signify the "beginning of another centered on mobile computing."

"Is this the start of an all-mobile Apple?"

This might not be about Apple at all: Maybe Serlet simply knew he had climbed as high as he could at Apple, says Darrell Etherington at GigaOM. He "could never become the company's CEO, thanks to many other well-qualified candidates suitable for the job." By leaving, he may get a shot at taking the reins at a smaller company.

"Apple's Mac chief departs as big changes come to OSX"