X-ray scanners won't hurt digital cameras or memory cards (but they WILL hurt film!)
However, your luggage gets put into a cargo compartment on the plane, and in the process it gets bumped around and tossed through the air by baggage handlers, and if it's on the bottom of the pile it might have hundreds of pounds of other luggage on top of it. The moral of this story is, don't put anything fragile in your checked bags without plenty of padding! This includes cameras, computers, and camcorders.
And there is also the absolute worst-case scenario - lost luggage. If your suitcase, with memory cards or camera, goes to Boise while you go to Orlando, you will be stuck having to buy new memory cards and maybe a new camera to get your vacation pics. And if you are one of those folks who has no rental car at WDW, you will be stuck paying the extortionist Disney prices for those replacement items.
Personally, I pack all of my camera and computer equipment in carry-ons, even the memory cards and batteries.