SAN FRANCISCO -- Heavy on the celebrity quotient and jam-packed with enough Apple (AAPL) technology to please the most discriminating fanboy and fangirl, the 29th Macworld opened Thursday for its annual three-day run at the Moscone Center.

With a fan-packed opening kickoff staring Hollywood heavyweights Ashton Kutcher and Josh Gad talking about playing Steve Jobs and Steve Wozniak in the upcoming feature film, "jOBS," this year's Apple-centric funfest seems to have an extra glow to it.

When Apple announced that the 2009 expo would be the last it took part in, some fans worried that the annual conference would be doomed, and that gloomy Mac-lovers would be left to wander aimlessly through a much-less-crowded Moscone Center.

Yet the fanboys keep coming back, perhaps just to bask in the afterglow of Jobs, who would appear regularly at the event to announce new products. The show this year expects about 25,000 paying participants, about the same number that came last year.

"We're really excited to have Ashton and Josh here because obviously the movie "jOBS" really resonates with our audience," said Paul Kent, the expo's general manager. "But the real star of the show, as always, is the product. And we'll have 265 companies represented this year, with about 100 app developers, all bringing new products to unveil."

One of those apps, a $20 beauty called iBird, was mesmerizing onlookers Thursday afternoon, as the sound of iPhone-borne bird calls filled the corner of the bustling exhibition hall. iBird's Crystal Adams calls the app "the most powerful search engine for birds out there. And it's sure easier to carry your guide in a smartphone than lugging around a bunch of books in woods."

She quickly described the process of using the app to figure out what kind of bird just flew over your head. "You start with the geographic region you're in, then select its shape, color, size and other attributes from 36 search attributes until you zero in on your bird."

Kent says the big themes at this year's show include the growing focus on and fascination with photography and videography done with the iPhone and iPad, as well as the exploding number of apps designed to help iPhone-toting musicians do their creative thing.

This year's show features a rich lineup of experts in all things Apple, from iPhoneography masters like Richard Koci Hernandez, to Matthew Purcell and students from his app-development class at Canberra Grammar School in Australia, who'll be visiting Silicon Valley for the first time to share their app-building tricks from Down Under.

Contact Patrick May at 408-920-5689; follow him at Twitter.com/patmaymerc.

Macworld
Described as the "the world's ultimate fan event for those who use, create and love Apple products," Macworld attracts Apple fans with all levels of skill and provides them their fill of speakers, workshops and hands-on demos of products and new mobile apps.
Where: Moscone Center -- West Hall, San Francisco
When: Thursday, Friday 10 a.m. to 5 p.m.
Saturday 10 a.m. to 4 p.m.
Ticket costs vary by package. For more details, go to macworldiworld.com/register.