Apple has scheduled an announcement for Sept. 5, sparking a new round of speculation that the computer maker was getting ready to unveil a line of iPods.

Apple sent out press invitations late Tuesday, notifying the media that the announcement would be made at the Moscone Center in San Francisco. The notification essentially confirmed reports on Apple enthusiast sites that the company planned to make a product announcement in early September.

Reports on Apple's plans focus primarily on a new line of iPods. AppleInsider reported last week that the new breed would be powered by a derivative of Apple's Mac OS.

The upcoming event also reignited speculation that Apple Chief Executive Steve Jobs would announce a deal to offer the long-awaited Beatles music catalog on iTunes. That rumor has been a favorite among Apple enthusiasts since the company in February settled its legal troubles with Apple Corps., the record company founded by the Fab Four.

The latest round of speculation and reports was good news for Apple investors. Shares of the company on Wednesday rose $5.72, or 4.5%, to $131.13 on the Nasdaq Stock Market. Goldman Sachs analyst David Bailey told The Wall Street Journal that the upcoming Apple event was "the almost certain launch of a new family of iPods."

Apple does not discuss future product plans in advance of formal announcements, but AppleInsider, quoting unidentified sources, said the company's iPod roadmap for the fall includes as many as four new models. The company is expected to unveil Mac OS versions of the video iPod and iPod Nano, according to the site.

Derivatives of the Mac OS is currently used in the Mac, iPhone, and Apple TV, so it would make sense that Apple would want to expand use of the operating system to the iPod. Samir Bhavnani, analyst for Current Analysis West, said running the new iPods on the Mac OS would turn the iPod from a "dumb device" to a gadget that Apple could develop a lot more software and services for. "The potential is here to raise the utility of the iPod," he said. "Suddenly, it can do other things. It's like putting a master's degree in iPod."

Bhavnani also said the iPod was in need of a facelift. "The iPod is due for a refresh," Bhavnani said. "What that would do for Apple is give customers a reason to buy new products heading into the holiday shopping season."

As to the Beatles catalog, Bhavnani said, "It wouldn't shock me if that announcement was made. It may be the 'one-more-thing' announcement." In launching new products, Jobs often adds surprise announcements at the end with the phrase, "One more thing."

While the iPhone has the same music and video capabilities of the iPod, the latter device is expected to remain attractive to consumers for some time. Besides being far less expensive, the iPod and other MP3 devices remain the favorites of consumers for downloading and playing music and video.

A recent study by JupiterResearch found that only about 5% of consumers surveyed reported transferring songs from their PCs to their mobile phones, and only 2% reported downloading songs over the air.

While the attention-getting iPhone could raise consumer awareness of music phones from other manufacturers, it's unlikely to change the current trend, JupiterResearch said. Instead, wireless carriers and handset makers must show real value of such capabilities.