What's the deal with black mold?

I seem to be hearing alot about black mold on the news lately, and my insurance no longer covers mold damage. What’s the deal with this black mold and why is it now becoming such a problem (in Texas specifically)? I can find lots of sites that give you a bit of information and offer solutions, but I can’t seem to find anything that’s comprehensive. Thanks for your help in advance.

I use this one:
http://www.schs.state.nc.us/epi/oii/mold/healtheffects.html

You can read around there.