I think the ancient Greeks would sympathize with the highs and lows experienced by the flash memory industry over the years. After all, it's been a business where many a company and investor have been burned by their hubris in the face of the gods of supply and demand. It looks to me as if SanDisk (NASDAQ:SNDK) was very mindful of this tumultuous past when it issued its 2010 guidance, and its stock is paying the price for the company's caution today.

On the heels of a blowout fourth quarter in which earnings came in at $1.18 per share, a full $0.48 above market estimates, thanks to a combination of strong demand and major cost reductions, SanDisk's 2010 sales and earnings guidance was pretty much in line with Wall Street's expectations. That didn't sit well with those who took a consensus-crushing forecast for granted, and thus the 13% decline that we're looking at today.

But take a quick look at SanDisk's recent earnings history, and it becomes evident that this company has developed quite the track record for lowballing forecasts. In addition to the Q4 blowout, SanDisk beat the market's Q3 2009 estimates by $0.49/share; its Q2 estimates by $0.52/share; and its Q1 estimates by $0.28/share.

So investors shouldn't be too surprised that the company is playing it safe with its 2010 forecast, especially since the NAND flash market is now a year removed from its most recent bottom, and there have been some predictions of relatively soft demand during the first half of the year, followed by stronger growth in the second half.

Strong demand, restrained supply growth
Looking at the overall demand outlook for 2010, it's easy to see how SanDisk could once again blow past its conservative forecasts. Research firm Informa Telecoms predicts 36% unit shipment growth this year in smartphones from companies such as Palm (NASDAQ:PALM), Research In Motion (NASDAQ:RIMM), and Motorola (NYSE:MOT), up from 33.5% in 2009.

You can count on these devices to keep shipping with growing amounts of flash. Meanwhile, as the economy picks up and flash manufacturing costs keep dropping, IDC expects demand for solid-state drives to accelerate from the 14% unit growth seen in 2009, with a 54% compound annual growth rate expected from 2008-2013.

Apple's (NASDAQ:AAPL) iPad, for its part, isn't expected to be a huge consumer of NAND this year, but in a business that looks like it'll be capacity-constrained, it could still have a big impact. While DRAMeXchange believes that the iPad will account for only 2% of NAND demand in 2010, it expects the device to boost industry prices (and thus SanDisk's margins) by making an expected second-half shortage even worse. These predictions of a supply shortage dovetail pretty well with restrained capital spending plans not only from SanDisk, but also from rivals Intel (NASDAQ:INTC) and Micron Technology (NASDAQ:MU); as well as with a cautious spending outlook given by SanDisk's joint venture partner, Toshiba.

As bad as the ticker looks today, there's still a lot for SanDisk investors to be optimistic about. The company's once-bitten-twice-shy caution might be doing a number on its shares right now, but chances are that it's only setting the stage for upward earnings revisions in the future.

Fool contributor Eric Jhonsa has no position in any of the companies mentioned. Intel is a Motley Fool Inside Value pick. Apple is a Motley Fool Stock Advisor selection. Motley Fool Options has recommended a buy calls position on Intel. The Motley Fool has a steady-state disclosure policy.