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Scott Jagow: This morning in San Francisco, Apple CEO Steve Jobs gives his annual keynote at the MacWorld Expo. It's one of the tech industry's most anticipated product announcements. Last year:

Steve Jobs: Today, Apple is going to reinvent the phone.

So, what's is gonna be this year? Marketplace's Dan Grech reports.

Dan Grech: The slogan for the 2008 Macworld Expo is: "There's something in the air." That has set off Internet speculation that Apple CEO Steve Jobs will unveil an ultralight laptop.

Joseph Jaffe: Before he even steps up to the plate, the world is buzzing with speculation.

That's Joseph Jaffe, author of "Join the Conversation," a book about the rise of conversational marketing. He says Apple uses this speculation as live market research -- that way ,Jobs can tailor his keynote address to maximum effect.

Jaffe: They've been very, very smart about being able to use that point almost as a ripple point or a pinnacle -- a conversation catalyst, in a sense.

Apple is also expected to unveil plans for a digital movie rental service on iTunes and an upgraded iPhone.

I'm Dan Grech for Marketplace.