Will the worlds problem of fresh water shortage be found in sea water?

Salt water can be converted into fresh water through filtering techniques (specifically reverse osmosis or electrodialysis) or by evaporation and recondensation (the water evaporates while the salt stays put, then the water vapor is cooled and collected as fresh water).

There are many places making use of this technology. In fact, there are around 1,500 plants producing about a billion gallons each day in the US. All the US plants, as far as I am aware, don't actually process seawater, however. They process brackish groundwater, which is less salty and half as expensive to process. The process would become viable in the US if it were cheaper (through improved technology or cheaper energy) or if other sources of water became more rare (and therefore more expensive).

What ever happened to the idea of towing giant icebergs from polar regions to populated areas at lower latitudes, as a source of nearly pure fresh water?

There are potentially downsides to that idea as well. The removal of large icebergs is sure to have some effect on their environment, but this may be negligible. More significant is the affect they could have on all the environments they must travel through to get from the artic to, say, southern California. The movement of a large quantity of ice through warmer water, especially the shallower sections, could cause a lot of damage to the local marine life. Another potential downside is the uncertainties in shipping this way. A problem with a single shipment could send the water market off-kilter while an the effects of an accident at, say, a single desalination plant could be alleviated by other plants on a temporary time scale.

That's not to say that this isn't a potential solution, but I thought I'd offer some of the cons.

Interesting -- the effects on marine life didn't occur to me.

Even a berg as big as, say, a cubic kilometer wouldn't really kill off that many critters, would it? I'd think that there would be fairly rapid mixing, and that the buoyancy of freshwater relative to seawater would keep the low-salinity layer near the surface until mixed.

Do you know if this has actually been studied?

Well if you want ice bergs you better grab them while they are there. It appears this thing called global warming threatens their very existance.....

It's not so much the salinity of the water as the temperature. Fish, being used to an environment whose temperature changes only very slowly, are vulnerable to quick drops in temperature such as those that would be caused by an iceberg travelling by, especially through shallow water. I don't know if anyone has done a formal study to find out how significant th impact would be.

And come to think of it, I'm not sure the meltwater would remain buoyed at the surface, rather than descending if it's cold enough.

This sounds like a job for computer modeling.

The whole idea sounded like an appealing alternative because desalination plants consume so much energy. But I wonder how much diesel fuel tugboats would have to use? Might not be worth it after all. Not to mention unsolved logistical problems of maneuvering, etc.