Note that the above rendering is in an arbitrary resolution. The 2d layout of the butterfly was done using xfig, and the 3D rendering was done using the excellent free raytracer, povray.
The distinctive butterfly logo gives the feeling of freedom, flight ("ma`of"), beauty - everything that reminds us of free software. The butterfly itself is composed of many bright "pebbles", symbolising the fact that the world of free software is made up from a bunch of bright individuals acting together to form a beautiful whole.
The choice of colors gives a feeling of youth, in addition to being a distinctive pair of colors that can be used in other places to symbolize our association. I belive the choice of the oblique camera angle, generating an assymetric look to the basically-symmetric butterfly shape, also gives a feeling of freshness.
Here are slightly saner sizes for the same picture:
It should be pointed out that a large software company already used a butterfly logo in one of its infamous campains (involving vandalism in NYC), and now uses it on one of their Internet services (hint: MSN.com). However, their butterfly looks nothing like this one - it contains a rainbow of colors, is not made of pebbles, and looks completely different. So there is no risk of confusion. I believe that their monopoly is already big enough - there is no sense in letting them also have a monopoly on an animal species that has long been associated with freedom.
The small logo is easy to use adjoining the name and description of the Amuta,
Or with just the name of the Amuta,
Or a tiny version of it can even be used as niqqud :)