The stock had fallen more than 80 points since December and has been getting pummeled in recent weeks by rumors of falling component orders and reports from bearish analysts — chief among them Bernstein Research’s Toni Sacconaghi, who estimated last week that Apple would miss its 2008 target of 10 million iPhones by more than 2 million units. With nobody from Apple stepping up to speak to these issues, the stock had nowhere to go but down.

But yesterday afternoon Cook talked for 45 minutes before at packed house at the Goldman Sachs Technology Investment Symposium, answering the questions that had been piling up — about inventory levels, iPod sales, unlocked iPhones, the timing of price cuts and the growth potential of the Mac.

There wasn’t much news — for the most part, he reiterated the company line — but for investors there was clearly something reassuring about hearing Apple’s strategy laid out clearly, calmly and for the most part without hype. That is to say, by someone other than Steve Jobs.

The main news to come out of the session was Cook’s repeated assurances that Apple is committed to hitting that 10 million iPhone target in 2008 and will do whatever it takes to make it — even if it means offering the iPhone to multiple carriers in some countries and selling unlocked phones. “We’re not married to any business model,” Cook said.

He also described the surprisingly large number of hacked iPhones turning up around the world as a good problem to have. When users are “stepping over each other” to get to a device, it’s a sign of pent-up worldwide demand.

He touched on most of the hot topics, saying among other things …

• There is “huge headroom” in the Macintosh market
• Apple TV is still a “nichey” product but has “enormous opportunity”
• iPod shuffle sales were down 17% globally last Q, thus the price cut
• 40% of iPod sales in U.S. are to new customers; that doesn’t feel like a saturated market to him
• The iPod touch is the beginning of a new mobile platform
• The $200 iPhone price cut last September was in part to grow the user base and attract developers
• No more detail about the SDK until next week to keep “the element of surprise”

Nothing terribly surprising there. But for some investors tuning in to the webcast, what he had to say was less important than how he said it.

“I was just impressed as I could be,” wrote one listener on TMO‘s influential Apple Finance Board. “I am always haunted by the vulnerability of Apple’s shareholders like myself if something should happen to Steve Jobs. For the first time, listening yesterday to Tim Cook made me feel confident that in him was a person who could ably step in if Jobs fell off the earth.” (link)

You can hear a replay of the webcast here. For more analysis, got to Techmeme here.