Considere solo las casillas de verificación modificadas en jquery

Una forma de hacer esto es usar .data() to store the original value of the checkbox.

$(document).ready(function(){
     $("input[type='checkbox']").each(function(){
        $(this).data("originalValue", $(this).is(":checked"));
    })
});;

$("#ok").click(function(){
    $("input[type='checkbox']").each(function(){
       var edited = $(this).data("originalValue") !== $(this).is(":checked");
       if (edited)
       {
           var checkboxLabel = $(this).next("label");
           alert("edited: " + checkboxLabel.text());
       }
    });
});

http://jsfiddle.net/8g3uz/3/

Original solution that checks for user interaction rather than change: http://jsfiddle.net/8g3uz/1/

To react to only those checkboxes being checked that weren't originally checked, Sugiero:

$('#check').click(
    function(e){
        e.preventDefault();
        var checkboxes = $('input:checkbox:checked');
        checkboxes.each(
            function(i){
                if (this.defaultChecked == false) {
                    // do something, it wasn't checked on page-load, eg:
                    alert("This is a checkbox that wasn't originally checked.");
                }
            });
    });​

Demostración de JS Fiddle.

To do something if the state has changed from the default, which seems to be the basis of your question:

$('#check').click(
    function(e){
        e.preventDefault();
        var checkboxes = $('input:checkbox');
        checkboxes.each(
            function(){
                if (this.defaultChecked !== this.checked) {
                    $(this).prev('label').addClass('changedFromDefault');
                }
            });
    });​

Demostración de JS Fiddle.

Usando el siguiente HTML:

<span>
    <label for="one">one</label><input id="one" type="checkbox" checked />
</span>
<span>
    <label for="two">two</label><input id="two" type="checkbox" />
</span>
<span>
    <label for="three">three</label><input id="three" type="checkbox" />
</span>
<button id="check">Check</button>​

This jQuery should show how to identify those elements that are changed, or unchanged, more easily:

$('#check').click(
    function(e){
        e.preventDefault();
        var checkboxes = $('input:checkbox');
        checkboxes.each(
            function(){
                if (this.defaultChecked !== this.checked) {
                    $(this)
                        .closest('span')
                        .removeClass('unchanged')
                        .addClass('changedFromDefault');
                }
                else {
                    $(this)
                        .closest('span')
                        .removeClass('changedFromDefault')
                        .addClass('unchanged');
                }
            });
    });​

Demostración de JS Fiddle.

Referencias:

• addClass().
• :checkbox selector.
• :checked selector.
• click().
• each().
• HTMLInputElement (para el defaultChecked property) at MDN.
• prev().

Here is a selector for the first case:

$("input[type='checkbox']:not([checked]):checked");

Here is a selector for the second case:

$("input[type='checkbox'][checked]:not(:checked)");

DEMO: http://jsfiddle.net/fascw/