Yep, I've modified your fiddle with lewsid's answer, and it works. http://jsfiddle.net/6enYL/1/
jQuery('#calendar').fullCalendar({
viewDisplay : function(view) {
var now = new Date();
var end = new Date();
end.setMonth(now.getMonth() + 11); //Adjust as needed
var cal_date_string = view.start.getMonth()+'/'+view.start.getFullYear();
var cur_date_string = now.getMonth()+'/'+now.getFullYear();
var end_date_string = end.getMonth()+'/'+end.getFullYear();
if(cal_date_string == cur_date_string) { jQuery('.fc-button-prev').addClass("fc-state-disabled"); }
else { jQuery('.fc-button-prev').removeClass("fc-state-disabled"); }
if(end_date_string == cal_date_string) { jQuery('.fc-button-next').addClass("fc-state-disabled"); }
else { jQuery('.fc-button-next').removeClass("fc-state-disabled"); }
}
});