For over 100 years, the light bulb didn't evolve much, generally sporting the same, well, bulbous design ever since Thomas Edison gave us the original in 1879. Lately that's changed as LEDs and CFLs have challenged the conventional bulb, and now Philips is taking light bulb design in a new, flatter direction.

The SlimStyle looks like a light bulb that's hit the gym. It emits light at a brightness equivalent to a 60-watt incandescent bulb, but it's powered by an LED (light-emitting diode), meaning it consumes just 10.5 watts. It also has a rated lifetime of 22 years, so you can count the number of times you'd need to change the bulb in a human lifetime on one hand.

The most novel thing about the SlimStyle, though, is its design. At first glance, it looks shaped like a regular bulb, but when you look at it from the side you can see how slim it is. It still fits in a normal socket, so it's not overly thin, but it's definitely unusual — and easier to screw in.

I got a little hands-on time with the SlimStyle. The light it produces is as warm as an incandescent bulb and it's extremely consistent, with no flicker. It feels more durable, too, with an exterior that's more like hard plastic than glass (though I didn't stress-test it). Unlike some of those twisty CFL bulbs, The LED-based SlimStyle is dimmable.

LED lights are considered by many to be the most promising candidate to fully replace the incandescent bulb since they consumer far less power and don't have the trace amounts of toxic mercury found in CFL bulbs. Starting Jan. 1 they'll get a big boost when a federal law goes into effect that will make it illegal to manufacture or import traditional 60- or 40-watt incandescents.

"Right now we're at a really exciting point because LED bulbs have started to break the $10 mark, and fall well below it once you factor in subsidies," says Sal Cangeloso, author of LED Lighting: A Primer to Lighting the Future. "We're still not at the point of mass adoption — it's not entirely clear where that is — but right now we have two significant factors coinciding: dropping prices and the the phase-out of 40W and 60W incandescents going into effect."

The Philips SlimStyle bulb goes on sale January 2 exclusively at HomeDepot.com.

Update: The bulbs cost $9.97 a pop.

Images: Mashable, Christina Ascani