var drag = $(".drag")[0];
    xPos = drag.offsetWidth / 2;
    yPos = drag.offsetHeight / 2;
    drag.addEventListener("touchmove", function() {
        event.preventDefault();
        $(this).css({
        'left' : event.targetTouches[0].pageX - xPos + 'px',
        'top' : event.targetTouches[0].pageY - yPos + 'px'
    });
});

$(".drag").each(function () {
    var drag = this;
    xPos = drag.offsetWidth / 2;
    yPos = drag.offsetHeight / 2;
    drag.addEventListener("touchmove", function() {
        event.preventDefault();
        $(this).css({
          'left' : event.targetTouches[0].pageX - xPos + 'px',
          'top' : event.targetTouches[0].pageY - yPos + 'px'
        });
    });
});​

// an array of all elements with class "drag"
// each element is wrapped
var drag = $(".drag");

// selects all matching elements, but then references
// the first raw DOM element in the array
var drag = $(".drag")[0];

var matches = $(".drag");

// each() executes a function for each matched element
matches.each(function () {
    var drag = this; // raw dom element

    // or, wrap to get jQuery object
    // var drag = $(this);
});​

var drag = $(".drag");

drag.on("touchmove", function(event) {
    xPos = $(this).offsetWidth / 2;
    yPos = $(this).offsetHeight / 2;

    event.preventDefault(); // preventDefault is IE-specific, is it?

    $(this).css({
        'left' : event.targetTouches[0].pageX - xPos + 'px',
        'top' : event.targetTouches[0].pageY - yPos + 'px'
        });
});