Yeah, you could do this with some CSS3.
You just add the following to .current.
.current{
color: #f00;
background-color: #000;
transition: color 0.5s, background-color 0.5s;
-webkit-transition: color 0.5s, background-color 0.5s; /* Safari */
}
Obviously you'll need to change color/background-color to the attributes you'd like to animate. Otherwise, Cubed Eye's suggestion of including JqueryUI is great, as the removeClass in jQueryUI will do it all for you..