With all this being studious BS lately, I realize I haven't been posing any real "content" (read: I'm about six months behind on my cyclingnews reading). For this I apologize, and will quickly try to make amends below:
Last year I talked a bit about how much I liked the Sram XX development (though I'm not entirely sold on 10sp drivetrains given that I already blow through two chains and a cassette a year), and when Shimano dropped the triple from their DA lineup in leiu of a compact double in '09, there was considerable hubub about how the world was changing (<---read this one, it's really good), but with Shimano now offering an off-the-shelf mountain double in the new SLX line (incidentally, with the gearing I run) and the XX taking "Best New Product" honors in the annual cyclingnews poll I think it is fair to say the triple crank is officially dead. If the XX sells as well next year as everyone thinks it will, it's likely Shimano will follow suit with a double offering as well. IMO, they're waiting to see how the non-standard SRAM BCD and 10 speed shifting sorts out in the market (the first, at least, is rubbish) before throwing their hat in the ring. They've already got plenty of pros out there hacking the current XTR to run double.
What does this mean for you? If you're cool, then you might as well start throwing out chainrings now. I, for one, will no longer go on a group ride where any bike has more than two of them unless one of the three is so damaged from rolling over logs that it only functions as a bashguard. Those of you who are artistically inclined might even be able to defray the cost of switching to a new, $470, standards-ignoring dedicated double setup by making some home appliances with your newly freed hardware.
This guy, for instance has realized that both triples AND CDs are dead, combining them artfully into one ironic timepiece:
While this guy has doubled his coolness by also ditching the small ring:
Don't be a loser. Lose a ring. Everybody's doin' it.