Many countries are banning the sale of incandescent bulbs over the next decade. Canada is planning on banning them in 2012 (not entirely sure if this is a done deal or not though), USA is banning them at different wattages starting in 2012 and ending in 2014.
The GU24 (two-pin) base is being introduced to force the transition, and prevent incandescent bulbs from being used in newer fixtures.
From this page:
What is a GU24 base and how is it related to CFLs?
- The GU24 socket and base system is designed to replace the Edison socket and base in energy efficient lighting fixtures. The ENERGY STAR® Program Requirements for Residential Lighting Fixtures, Version 4.0 require that residential lighting fixtures cannot use the standard Edison screw base, even if they do not have a built-in ballast. The same requirement is included in California's Energy Efficiency Standards for Residential and Nonresidential Buildings, known as Title 24-2005. This requirement is designed to insure that fixtures that receive ENERGY STAR® qualification when using an energy-efficient self-ballasted CFL, or are qualified as energy-efficient under Title 24-2005 cannot be operated with an incandescent lamp. The GU24 socket was designed to be compatible with these energy efficiency regulations. The GU24 base has two dual-diameter pins; the smaller portion having a diameter of 3.4 mm (0.13 inches) while the larger portion has a diameter of 5 mm (0.2 inches). CFLs with a GU24 base are designed to be connected directly to the power line, so they are functionally equivalent to screw-base CFLs instead of normal pin-base CFLs. Unfortunately, ENERGY STAR® refers to CFLs with the GU24 base as self-ballasted pin base lamps, a designation that may lead to confusion with pin-base CFLs that do not have an integral ballast. Some manufacturers are also making modular ballasts with a GU24 base on one end and a socket for a normal pin-base CFL on the other. These modular ballasts can be used to adapt normal pin-base CFLs to fixtures that have the GU24 socket, thereby reducing the amount of material that must be thrown away when the lamp fails.
I would bet Edison will not disappear for quite a while though: there are hundreds of millions of fixtures, and it's not practical (or environmentally friendly) for everyone to go out and replace every fixture in the next few years. My guess (and I have no authority in the matter btw :)) is that it will be 2015-2020 before you start finding more GU24 base bulbs than Edison.
Also, you can get Edison to GU24 adapters, which means even if Edison bulbs themselves disappear, you can still use your existing fixtures.