Because Apple's support policy is muddied -- it does not spell out how long it continues to patch an OS X edition -- the faster cadence will either require it to simultaneously support more operating systems, or cut short support of editions used by millions. Either would be a marked departure for the company.
Apple has already reached that point because of the two back-to-back releases of Lion and Mountain Lion. Previously, Apple patched only "N" and "N-1," where N was the newest edition, and halted support for N-2 about the time it shipped N. Instead, Apple patched Snow Leopard last fall, months after Mountain Lion's launch, and may again in the coming weeks, when the company is expected to upgrade Mountain Lion to 10.8.3, and patch Lion.
Come July or August and the debut of OS X Next, Apple may be forced to keep patching Snow Leopard -- at that point it would be N-3 -- because Snow Leopard will still account for approximately 23% of all Macs.
Microsoft will face the same issues if, as rumors have hinted, it quickens the release cadence for Windows by also shifting to an annual schedule. The first such upgrade -- or update, since its extent is still unclear -- has been designated "Blue" by bloggers, who claim that it will appear this summer.
Apple's practice is to reveal its newest OS X at the company's annual Worldwide Developers Conference (WWDC), which is held in San Francisco in June. It starts selling the upgrade several weeks later, probably via only the Mac App Store, like last year, and at the same $19.99 price.
According to the current schedule of the Moscone Center, where Apple has hosted WWDC since 2003, the week of June 10-14 is the only five-day stretch starting with a Monday that is not already booked. If that is the week of WWDC -- which Apple has yet to announce -- it would unveil OS X Next during the opening keynote on June 10.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is email@example.com.