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;
}