Useful links, factor30.
It is a serious problem, perhaps more worrying than the current fave swine flu. Bees don't just pollinate flowers they play a vital role in pollinating food plants. If the number of bees is in serious decline then will ouragriculture industry survive? Image no fruit, veg or cereals.
No one has an accepted explanation for the so-called Colony Collapse Disorder, but it's likely to be a mixture of the Nosema microbe, the Varroa mite and something else that hasn't yet been identified.