optimise jquery code

Here's a breakdown of what I did to your code to optimize it. I din't test it though since nothing really happens on jsFiddle. But comments on the code will help:

//cache commonly used elements
//or example, the following calls jQuery to make them into jQuery objects
//you previously did this on every event handler
var localeSelect = $("#locale-select"),
    localePop = $('#locale_pop'),
    footer = $('#footer'),
    localeSelectLabel = $(".locale-select-lable");

//follow the natural progression of parsing, which would be:
//- variable declaration
//- function declaration
//- operations
//for more info, research on the difference of 
//function declarations and function expressions and how they are parsed
function closeSelector(hide_type) {

    //personally, I go for the comma separated, single var keyword approach
    //it emphasizes the variable block
    //but it's up to you. 
    var foot_height = footer.innerHeight(),
        select_position = '+=' + (Number(400) + 20);

    if (hide_type == 'slide') {
        localeSelect.animate({
            top: select_position
        }, 1000, function() {

            //according to jQuery, the value of "this" is the DOM element animated
            //but you already have reference to localeSelect, a jQuery object
            //wrapping "this" in jQuery is redundant. use the reference instead
            //saves you one function call
            localeSelect
                .removeClass('open')
                .fadeOut();
        });
    } else if (hide_type == 'disappear') {
        localeSelect
            .fadeOut('fast')
            .removeClass('open');
    }
}

$('#region-picker').click(function() {

    var foot_height = footer.innerHeight(),
        foot_height_css = foot_height - 1,
        select_position = '-=' + (Number(700) + 18);

    //although allowable, but it's better you use braces for code blocks        
    if (localeSelect.is(":visible")){
        return closeSelector('slide');    
    }

    localePop.fadeOut();

    //chainability is a good asset of jQuery
    //so as long as the previous call returns the same object
    //you can chain a function that operates that object
    localeSelect
        .css({
            top: foot_height_css
        })
        .fadeIn(function() {
            $(this)
                .addClass('open')
                .animate({
                    top: select_position
                }, 1000);
        });
});

$('#select-tab').click(function(e) {
    e.stopPropagation();
    closeSelector('slide');
});

localeSelect.click(function(e) {
    e.stopPropagation();
});
$(document).click(function() {
    if (localeSelect.hasClass('open')) {
        closeSelector('disappear');
    }
});

$('.locale-link').click(function() {
    var flags = $(this).attr("class").match(/(margin\w+)\s/g),
        flagClass = "tk-museo-sans locale-select-lable" + (flags.length ? " " + flags[0] : "");


    localeSelectLabel
        .html($(this).html())
        //just wondering, is this an "erase all classes and replace with" operation?  
        //jQuery has a convenient .addClass(className) function        
        .attr("class", flagClass); 

    closeSelector('disappear');

});

$('#locale_pop a.close').click(function() {

    //i see the name of the cookie redundantly
    //why not store it in one location and use that variable?
    var cookieName = 'show_blip_count',
        show_blip_count = readCookie(cookieName);

    if (show_blip_count < 3) {
        eraseCookie(cookieName);
    }

    //in both operations, you create a cookie, why not factor it out?
    createCookie(cookieName, 3, 360);

    localePop.slideUp();
    return false;
});


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