The Icelandic finance minister was flying to the UK (or was it NY) to have some talks about the crisis, he was so worried about the banks collapsing, he brought cash in case his credit card stopped working while he was travelling...
I take a bunch of cash when traveling regardless of banks being about to collapse. The electricity can go out anytime. And since I am traveling, especially internationally, I might not have access to a network or community I can call on, so it seems prudent to have a rigorous plan B.