This uses cookies to set a preference of open or closed, threads are closed by default. Just download the cookie plugin and link it in your header.
$("#togglecomments").click(function(){
var hideTxt = p2txt.hide_threads;
var showTxt = p2txt.show_threads;
if (hidecomments) {
commentLoop = false;
commentsLists.hide();
$.cookie('threads', 'hidden');
$(this).text(showTxt);
} else {
commentsLists.show();
$.cookie('threads', 'shown');
$(this).text(hideTxt);
}
hidecomments = !hidecomments;
return false;
});
var threads = $.cookie('threads');
if (threads == 'hidden') {
commentsLists.hide();
$(this).text(showTxt);
};