This chap has a shellshock fix for older Macs, including PPC and pre-Mountain Lion. I tested it on a Macbook Pro (Intel) with Leopard 10.5.8 and it works fine.
It is also an easy way to fix failed bash update attempts, as it’s a single file that you can copy over /bin/bash and /bin/sh. (If you borked bash and can’t open a Terminal window now, just type in the command “ksh”.)
The one good thing that has come out of shellshock is that the bash debugger runs on bash4, so that will be good for wider adoption.
Now if only Microsoft would get that Skype update out for older Macs. (Instead, they’re actively blocking old versions that used to work fine.)