I was playing with Trends today and noticed they have added a metric that averages the weight of each keyphrase you enter and compares it against the first phrase entered. Very handy. Unfortunately they have also added max number of queries per day and I got this message:
Never heard about but i think it might be Cookie based or by logging your IP Address unless you are logged in to your Google Account...! After all you can get rid of that error by simply using any anonymous proxy out there