At the end of this year, U.S. manufacturers will no longer be allowed to sell 100-watt incandescent bulbs. The 75-watt bulb will be fazed out in 2013, while 40 and 60 watts won't be sold after 2014.
It's all part of an effort to make the United States more environmentally friendly, which also saves you money. So instead of those old bulbs, you'll soon have the option to purchase energy efficient replacements in the form of halogen, CFLs and LEDs. That also means new terminology, as watts officially become lumens.