Be worried. I spoke this weekend with Jeff, a guy on my civil war shooting team who happens to head up the bee association here in NC.
There have been meetings and discussions all over the country about this, and word is getting to Washington, as a die-off of this level could cause famine world-wide, since bees pollinate 1/3 of our food crops worldwide.
They are looking at aspergillis, which was found on doing autopsies on bees found in the die off sites. They've also found some sort of organism in the bees, and are investigating possible use of certain pesticides used on crops.
At this point, no conclusive evidence has been produced, but the entire beekeeping community is on high alert, and as the winter wanes, it is expected that many, *many* more hives will be discovered to be missing.
Wolf-tracker, this is most definitely *not* a care issue. Guard your bees well, this is a very real problem, and one that is receiving world-wide attention.
I'll provide any updates I get from my bee-keeping folks, and drop a line to Dewey Caron, an entymology professor at U. Delaware, see what he has to contribute.