Few events can steal the thunder from an Apple Inc quarterly earnings day -- an Apple product launch is one of them.

The company released its quarterly results on Monday, but Wall Street is waiting for Wednesday, when Apple is expected to unveil a new tablet computer that investors hope will be as huge a phenomenon as its iconic iPod and iPhone.

Along with its strong earnings -- Apple posted big gains in profit and revenue in the December quarter -- a successful tablet launch could provide a long-term catalyst for the company's stock. Although the tech giant's shares often sell off right after major launches after months of rumor fuel big expectations.

On Tuesday, Apple's shares jumped higher, rising as much as 4 percent before closing up 1.41 percent at $205.94.

Little is known about the device, despite a rabid fan base, which speculates on everything from the component makers to its shape and form. Industry watchers are bullish. They say Apple's obsession to detail gives the so-called iSlate a big edge in a computer category that had been deemed a failure.

If Apple is going to design a product, then it's going to be the best design in the marketplace, said Broadpoint Amtech analyst Brian Marshall. To bet that it's going to be a flop is a bad bet.

Most analysts have not factored the tablet into estimates for fiscal 2010, but sell-siders have been busy lifting price targets on Apple's stock in the past month.

To be sure, Apple is setting itself quite a task, one that has frustrated previous attempts: to sell consumers on the value of a device that sits somewhere between a full-sized laptop and a pocket cellphone.

The device is hyped as a do-everything, go-everywhere touchscreen media gadget that bridges the gap between smartphones, laptops and electronic readers. Magazine, book and newspaper publishers are reportedly talking with Apple about providing material.

There's a huge potential long-term story there for Apple, said Atlantic Equities analyst James Cordwell. Whether they get it right the first time, we'll have to wait and see, but they have a pretty good track record.

Wall Street will pay particular attention to the tablet's price tag. If it is closer to $1,000 than $600, analysts say it will be tougher to convince consumers to buy.

Apple could offer it under carrier-subsidized plans -- Verizon Wireless is frequently mentioned -- which might help take the bite out of the purchase price.

Analysts believe Apple will sell 2 million to 5 million tablets in the first year.

The device could add $1 per share to Apple's non-GAAP earnings in the year, and generate $2.8 billion to $3.5 billion of revenue, with a $700 average selling price, said Cross research analyst Shannon Cross.