Your digital camera and memory cards will be perfectly safe going through the x-ray scanners. Airport X-rays have no effect on magnetic media such as memory cards, so your cameras, memory cards, PDAs, laptops, iPods, cell phones, and other electronic devices are perfectly safe going through the x-ray scanners.
However, I always pack my camera gear and laptop in a carry-on bag, because I have had horrible visions of my beloved Digital Rebel or WillPAQ (my Compaq Presario laptop) being used as a football by the baggage handlers.
I have sat in my seat and watched the handlers loading luggage into the plane, and they are not terribly gentle.