Is there a way to make a DIV unselectable?

I wrote a simple jQuery extension to disable selection some time back: Disabling Selection in jQuery. You can invoke it through $('.button').disableSelection();

Alternately, using CSS (cross-browser):

.button {
        user-select: none;
        -moz-user-select: none;
        -khtml-user-select: none;
        -webkit-user-select: none;
        -o-user-select: none;
}