You can use .hover(). It's can be used like so:
$("selector").hover(
function (){
//mouse over
},
function (){
//mouse out
}
);
An example of it's use from the documentation is here:
$("li").hover(
function () {
$(this).append($(" ***"));
},
function () {
$(this).find("span:last").remove();
}
);