Although the study quoted by the OP got a lot of media attention because of MIT involvement, what is more interesting is this actual product that has been released last month: "One AAA battery! The boss must be kidding..."
This company (Silicon Labs) has managed to put a DC-DC converter in a microcontroller and have managed to do this on an actual product that you can buy now (not just a research project!). They claim to be able to run for years (even >15 years) on typical low-power applications such as data loggers that wake up for a short while take a measurement and go to sleep. This is also the first microchip that can run on one battery... if you think that adding an external DC-DC converter would do the same trick, you have to remember that the external DC-DC converter needs to be ON even during sleep mode so the micro can wake up again, which burns quite a bit of power. They claim to have eliminated this by putting the DC-DC converter on chip.
More articles on this micro: http://www.eetimes.com/news/semi/showArticle.jhtml?articleID=206801775 http://www.electronicsweekly.com/Articles/2008/02/26/43201/silicon-labs-microcontroller-features-integrated-dc-dc-for-portable-uses.htm