Apple acknowledge April 12 that its highly anticipated new Mac OS X 10.5, which the company is calling Leopard, will be delayed until at least October, although developers could have a beta version by June.

The Cupertino, Calif., company announced the delay in a statement released April 12. The reason, according to Apple, is that members of its engineering team were pulled from the project to work on the software for the iPhone.

After much speculation, CEO Steve Jobs unveiled the Apple iPhone at the Macworld Expo in San Francisco in January. The iPhone, which will initially cost $499 for a 4GB model and $599 for an 8GB model, is still slated for a June release but needs approval from the Federal Communications Commission.

Apple's statement claimed that the company had been preparing for a full Leopard release at its Worldwide Developers Conference in June, but concerns with the iPhone software meant that the company had to delay the new operating system.

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According to Apple's statement, "the iPhone contains the most sophisticated software ever shipped on a mobile device, and finishing it on time has not come without a price—we had to borrow some key software engineering and QA resources from our Mac OS(R) X team, and as a result we will not be able to release Leopard at our Worldwide Developers Conference in early June as planned."

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The company does plan to show off the new OS to developers at the WWDC and also distribute a beta. Apple then hopes to ship a full version of the operating system to its customers sometime in October.

"While Leopard's features will be complete by then, we cannot deliver the quality release that we and our customers expect from us," according to Apple.

Steve Baker, an analyst with NPD Group, said that Apple, like any other company, only has limited engineering resources and executives appeared to have made a decision that brining the iPhone to market on time was more important than having Leopard ready by June.

"Apple had two very large projects going on at that same time and they appear to have decided that a delay in the iPhone was more costly than a delay with Leopard," Baker said. "They took a calculated chance."

Apple has kept quiet concerning the details of Leopard. In the past few months, the company has mainly focused on the iPhone and its new deal with the EMI record label to sell music through iTunes without DRM (digital rights management) software.

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The release of Leopard has been closely tied with demand for Apple's Mac desktops and notebooks. Some analysts believed that the arrival of the operating system would help boost Mac sales.

In a research report released before Apple announced that it would delay Leopard, Shaw Wu, an analyst with American Technology Research, wrote on April 12 that Leopard would lead to greater Mac sales later this year.

Apple is schedule to release its latest financial results on April 25, and the company's Mac sales are predicted to decrease from previous quarters.

"Based on our analysis, we believe Macs will likely come in towards the lower-end of expectations [1.37-1.5 million units] due to a pause ahead of Mac OS X Leopard's launch and anticipation of new high-end 8-core Mac Pros," Wu wrote in his report.

For his part, NPD Group's Baker believes that Apple was willing to risk a delay in the hopes that its back-to-school sales would not suffer and that the success of the iPhone would overcome the Leopard delay.

"They seem comfortable enough with their PC business and they are willing to risk that a delay would not have that great of an impact," Baker said.

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