Well, I programmed the lockbits so that you can't over write it, but the lockbits seemed to unlock itself on some of the Axons. Could be an AVR Studio bug . . .
To overwrite the bootloader, the lookbit has to be unlocked, and you would have to write code that explicitly overwrote memory in the boot section. Writing to random address locations could do it.
Its pretty hard to do by accident . . .