As of next month, it will be our pleasure to move organic LED (OLED) displays out of Ars's informal "three to five years away" category, where it will join fellow 3t5YA alumnus E-Ink in the mass market. Right now, there's a trickle of OLED-sporting devices poised to come to market in the fourth quarter of this year, but economies of scale should take hold and the screens should get cheaper, turning that trickle into a flood. But the shift to OLED will have some unexpected consequences for battery life, which in general will be better than it is for LCD-based devices—with a caveat.

We've already seen OLED in some boutique devices like the now-defunct OQO Model 02, but OLED's true break-out product will be the forthcoming Zune HD. The device, which is slated for a September launch, has an 3.3" active matrix OLED (AMOLED) touchscreen that's already generating excitement, even among some die-hard iPhone fans. Then there's the new Nikon Coolpix S70, also launching in September, which sports a 3.5" OLED touchscreen that covers the entire, buttonless back of the device.

If rumors are to be believed, Samsung's OLED-packing Omnia II may get the jump on September with an August 23 release date. This will be but one of a number of OLED devices planned by Samsung, which has invested heavily in the technology. Some of these Samsung products are destined for Sprint's network sometime in the fourth quarter, where they'll team up with the Pre as part of Sprint's effort to lure customers away from the iPhone.

LG is also a big OLED backer, and is rumored to be planning a December launch for its 15" OLED display in Korea. Don't bother saving up for one of these, though, because a panel this size will be a multiple of the price of a vanilla flat panel. OLED has a barrier to jump before it makes sense at larger sizes, since companies like Samsung will have to shell out to get fabs for the larger panels up and running. Don't expect that process to start until global credit markets loosen up and consumer demand for premium products returns.

One of the big variables with OLED displays is battery life—an OLED's power consumption varies greatly with the gray level of the image it's displaying. Bright images with low gray levels consume much more power than darker images with higher gray levels, as shown by the slide below, which came from a May 2008 OLED presentation.

Though it's not apparent from the slide because of the selection of sample patterns, power draw varies pretty linearly with mean gray levels, and the range is fairly wide. This inconsistency may have some implications for interface design.

For instance, black backgrounds will be the rule on these devices, and it's likely that e-book apps may end up using white text on a black background. I imagine that video playback will probably even out, so that most videos will end up drawing similar amounts of power. Ultimately, though, what's on the screen will have an impact on battery life, and will give mobile users one more variable to tweak in their never-ending quest for a few extra minutes of usage time.