I can confirm this is a bug, I have reproduced it with 3 different USB sticks all of which have worked in the past with usb-creator.
I have tested with both jaunty-desktop-i386.iso and jaunty-desktop-amd64.iso, the RC candidate isos. I have also tested booting those USB sticks on 3 different machines, all get the same busybox prompt. Disabling the persistent storage works.
I can confirm this is a bug, I have reproduced it with 3 different USB sticks all of which have worked in the past with usb-creator.
I have tested with both jaunty- desktop- i386.iso and jaunty- desktop- amd64.iso, the RC candidate isos. I have also tested booting those USB sticks on 3 different machines, all get the same busybox prompt. Disabling the persistent storage works.