Right-click traps are really lame because they inconvenience good people, and they do not stop bad people.
Think of this: do you really give a damn if someone grabs one of your images and uses it as a background ? In which way does this damage you ?
And again: the "professional" image thief will have an arsenal of tools that will tear through your puny JavaScript like a tank through a strawberry field.

Images can be sucked off a website with any number of non-interactive web clients, like wget. They take residence in the user's cache. And JavaScript can (luckily) be turned off.
Sure, you can make JavaScript mandatory for browsing your site (and you can force users to run Explorer: in which case, bye bye Linux users), but are you sure you have enough unique, compelling, precious content that users will put up with the inconvenience ? Remember, this is still a browser's market, in other words there is an abundance of sites and a scarcity of eyeballs.
And sites that really have content somewhat seem to ignore the issue. Right-click trapping appears to be an obsession of budding graphic designers and photographers fresh out the egg, terrified that someone will steal their images. I understand that that can be a concern, but right-click trap is not the solution.