As function .toggle(fn1, fn2...) deprecated (See: http://forum.jquery.com/topic/beginner-function-toggle-deprecated-what-to-use-instead)
You can do like this:
var clicked = true;
$("#powersettings").click(function () {
$("#powermenu").toggle();
$(".content, .tab").toggleClass('blur');
if (clicked) {
$('#tab a').off('click',foo);
clicked = false;
}
else {
$('#tab a').on('click',foo);
clicked = true;
}
});
Here is a fiddle(http://jsfiddle.net/android/3U4sK/1/).
As your updated code, the foo function should like this:
function foo(e){
hideContentDivs();
var tmp_div = $(this).parent().index();
$('.main #content').eq(tmp_div).fadeIn(2000);
}