Some informational blogs I have found on the disaster include
Dr. Jeff Masters' WunderBlog,
Michelle Malkin, and
The Irish Trojan. You can find a lot more information by googling for "katrina blog" or similar terms. It is pretty clear from reading these that blogs are indeed providing much more in-depth information than the major media is.
There are reports of widespread communications failures, but it is rather clear from looking at the blogs that data is still finding its way to the Internet. Although the infrastructure is destroyed, it appears that people are providing that missing link to the net that the destroyed infrastructure cannot. Blogging and the Internet seem to be holding up just fine to this trial by wind and water, and providing a valuable service beyond anything available anywhere else.