This is a neat project indeed. My guess is a small gearmotor, although I can think of a couple of ways to do it using a small motor similar to the vibration motor in a pager. Then a PWM drive to slow it down, and it is done, except if it needs to be checking for movement to tigger the motion.
But this project could indeed be the start of another fad.
He purchased the butterfly as seen in the photos, I'm not sure what the wings are made of but it looks like some fairly thin cloth/nylon/spandex type material. In the Instructable he says that the wings will be finished in fabric that matches the dress.
A moving mechanical butterfly in your hair would really turn some heads. It seems that DelFly is on to something similar although they could use some tips in making their ornithopters more "butterfly" looking. And, of course, remove the camera as well. Getting it to alight on top of the brides hair whilst in the course of reciting her vows would also get a few "wows".
Some of this technology has been perfected and mass marketed in the RC helicopter and airplane world. Minature recievers, lithum ion batteries, tiny servos made from motors and a leadscrew occuping less than 1/2 of a CC. The green led in this case tells the operator that the system is powered and ready. I would have modified a Ready to fly Blade MCX which costs $135 and includes a co-axial 4 channel helicopter, 4 channel radio, battery and charger...
New versions of BASF's Ecovio line are both compostable and designed for either injection molding or thermoforming. These combinations are becoming more common for the single-use bioplastics used in food service and food packaging applications, but are still not widely available.
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.