Most US carriers have made it easy for subscribers to donate to the Red Cross for hurricane Katrina relief:
All carriers are still working to get their networks back to 100%. Communications is typically the first and most important service to bring back up after a major disaster.
Your donation is also welcome directly on the Red Cross' website.
As a Cingular customer, I have not recieved a text message.
Cingular only sent text messages to their customers on the East Coast so far.
For verizon, it is actually "2HELP" or "24357" -- not 2give as its listed on the frontpage.