The recent past was much better than expected. The near term future is uncertain. And the long-term looks great.

That’s about the way I’d sum up Corning’s (GLW) second quarter report released before the opening bell on July 27.

For the quarter just completed–the recent past–the company reported earnings of 39 cents a share versus Wall Street expectations for 32 cents a share. Revenue climbed to $1.395 billion for the quarter. That was an 18% decline from the second quarter of 2008, but a big 41% increase from the first quarter of 2009.

Corning saw strength across its product line with a 66% increase in total LCD glass for TV screens and similar uses from the first quarter of 2009 and a 14% increase in sales from its telecommunications business on growth in demand for optical fiber from China and in North America from the roll out of fiber to the home from companies such as Verizon (VZ). That latter business is getting a boost from a new Corning technology, bendable fiber, that makes it much easier to get optical fiber to homes and businesses.

Gross profit margin climbed to 41% from 27% in the first quarter.

But Corning said that the third quarter, while strong, wouldn’t show anything like the quarter to quarter growth the company saw from the first to second quarter of 2009. Glass shipments in the third quarter, for example, will be flat or slightly up in comparison to second quarter levels, said CFO James Flaws.

The company did raise its forecast for total industry LCD glass volume to 2.3 billion square feet for the year,  but that was only up slightly from the company’s forecast of 2.1 to 2.2 billion square feet for 2009 that it made early in the second quarter.

Looking out to the rest of the year, why wasn’t Corning more gung-ho?

Basically  because Corning isn’t certain that customer demand is going to outstrip supply for the rest of 2009. A good part of the increase in LCD sales Corning saw in the second quarter was due to customers rebuilding inventory in anticipation of the seasonally stronger demand for TVs and other electronics. Supply chain inventories, the company said, have now been rebuilt to the level of inventories at the end of 2008.

But now that inventories have been rebuilt will customers keep ordering? Forecasts, Corning noted, are for retail demand to grow by double-digit rates in the last half of 2009.

And that sets up two worries.

First, Corning’s customers could take a wait and see attitude on retail sales before reordering glass from Corning now that they’ve rebuilt inventories.

Second, Corning’s competitors could ramp up supply causing selling prices, which were stable in the second quarter, to plunge again. Everybody, Corning included, has lots and lots of idle capacity that they could bring quickly back on line. Bring those factories back into production too fast and the market will be flooded with more product than anybody can sell.

All this is about the near-term future. What we’re seeing is the normal, but painful and uncertain, rebalancing of supply and demand that comes after a boom goes bust. Everything in the short-term numbers for the second quarter, though, says Corning’s long-term future–the reason it’s in my long-term Jubak Picks 50 portfolio–stays on track.

(Full disclosure: I own shares of Corning in my personal portfolio.)