A gaunt-looking Steve Jobs stepped back into the spotlight for the first time in more than half a year on Wednesday, unveiling new iPods for Apple Inc and drawing a standing ovation.

But Apple's shares fell nearly 2 percent after hitting a year-high earlier in the session, with some analysts remarking on how thin the 54-year-old chief executive appeared.

Dressed in his trademark black turtleneck and jeans, Jobs took the stage and thanked everyone in the Apple community for their heartfelt support. It was his first public appearance since returning to work in June after six months of medical leave, during which the charismatic corporate showman underwent a liver transplant.

I now have the liver of a mid-20s person who died in a car crash and was generous enough to donate their organs. I wouldn't be here without such generosity, an emotional Jobs told the audience, exhorting them to all become organ donors.

Apple shares initially rose about 1 percent to a year's high before retreating to trade down 1.6 percent at $170.14.

I'm sure (Jobs) looking so frail -- the guy's had the most extreme surgery you can have -- didn't help matters, but I think people have come to grips that the torch is going to be passed, it's just a matter of when, said Dave Rovelli, managing director of U.S. equity trading at Canaccord Adams.

Jobs, a pancreatic cancer survivor, started off by announcing a new version of Apple's popular online media store, iTunes, and updated software for the iPhone.

He then unveiled new iPod features and colors, including adding a video camera to the iPod nano, as well as price cuts for other models, ahead of the crucial holiday season.

Analysts had expected an appearance by Jobs to give Apple's stock a boost. The shares rose in the afternoon to $174.47, their highest since August 28, 2008. But they quickly retreated.

While he was gone, Apple innovated and the product pipeline is set for the next three years, said Canaccord Adams analyst Peter Misek. He is clearly a genius. It's great to have him back. It's great for the industry, but I don't think he's back full-time and I don't think he's going to come back full-time.

RUMORS OF MY HEALTH

Jobs's return is well-timed. The holiday season is a critical period for Apple, as it is for many consumer electronics companies, as shoppers fill stores and spend their precious discretionary income on the latest gadgets.

December-quarter sales made up around 30 percent of Apple's revenue last fiscal year.

Jobs stepped away from day-to-day operations in January after months of rumors about his health and noticeable weight loss. He returned early this summer, but had not been seen at a public event until Wednesday.

As expectations of a high-profile product launch faded in the run-up to the event, much of the speculation centered on whether Jobs would appear.

Some analysts had speculated that Jobs would not turn up so as not to steal the spotlight from Apple's new products. Others had seen him taking on more of a behind-the-scenes role, despite his demonstrated talent for pitching products, as other executives step to the forefront.

But Jobs is also famous for his attention to detail and the huge amount of control he exerts over Apple and its products.

Our larger point about Steve is that no single individual designs products as complex as the iPhone and Macs and Leopard. They are far too complex to assume that one individual does that, and markets it and brands it. Apple has a phenomenally deep bench, said Daniel Ernst at Hudson Square Research. (For a photo, please click on http://blogs.reuters.com/photo/2009/09/09/live-from-the-apple-media-extravaganza/

(Additional reporting by Clare Baldwin; writing by Edwin Chan; editing by Andre Grenon and Maureen Bavdek)

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