As part of a lengthy post discussing Apple's nearly singular focus on iPhone OS 4 over the past few months, Daring Fireball's John Gruber reports that he is hearing that resources have been diverted from the Mac OS X team to the iPhone OS team. Consequently, Gruber offers an "educated guess" that Mac OS X 10.7 may not be introduced to developers until mid-2011.

A few months ago, I heard suggestions that Apple had tentative plans to release a developer beta of Mac OS X 10.7 at WWDC this June. That is no longer the case. Mac OS X 10.7 development continues, but with a reduced team and an unknown schedule. It's my educated guess that there will be no 10.7 news at WWDC this year, and probably none until WWDC 2011.

Evidence of Apple's work on Mac OS X 10.7 surfaced last November. By January when Gruber reported that he was hearing of a possible developer release for Mac OS X 10.7 at Apple's Worldwide Developers Conference 2010, usage of the next-generation operating system already seemed to be on the rise within Apple's campus.

The time between major Mac OS X releases has been increasing as the operating system matures, with a nearly 30-month gap between Tiger and Leopard being followed by a 22-month wait for Snow Leopard, which Apple positioned primarily as a refinement of Leopard. With Mac OS X Snow Leopard having been released less than eight months ago, it would not be surprising to see Mac OS X 10.7 not make its public debut until late 2011 or beyond, even without iPhone OS 4 putting pressure on development.