[jquery] jQuery If DIV Doesn't Have Class "x"

$(".thumbs").hover(
    function(){
        if (!$(this).hasClass("selected")) {
            $(this).stop().fadeTo("normal", 1.0);
        }
    },
    function(){
        if (!$(this).hasClass("selected")) {
            $(this).stop().fadeTo("slow", 0.3); 
        }           
    }
);

Putting an if inside of each part of the hover will allow you to change the select class dynamically and the hover will still work.

$(".thumbs").click(function() {
    $(".thumbs").each(function () {
        if ($(this).hasClass("selected")) {
            $(this).removeClass("selected");
            $(this).hover();
        }
    });                 
    $(this).addClass("selected");                   
});

As an example I've also attached a click handler to switch the selected class to the clicked item. Then I fire the hover event on the previous item to make it fade out.