Not only toblerone, what about Mars bars?
Some years ago you had the standard mars bars, then they brought out a pack with two bars in it but smaller, so you actually got around a 1/3rd more chocolate. Then a year later the big standard bar dissapeared, so did the double pack - they split it into single bars which were 25 grams smaller than the orginal but the price increased as well.
Eventually and I do hope it is soon, the were will be a backlash as people realise they are being ripped off and just stop buying them.
Oddly enough here in Spain, confections like this don't really sell - in fact most sweet products are hard to find, only in large supermarkets or small english run establishments. Sweet shops like the UK don't exist.