See my page entry in main wikipedia site: Neolux
The design choice for this was to take elements from the design of the foundation logo, and re-purpose them.
The gestalt of the logo is effectively a talking head. The arcs being stylised sound waves as the circular head says something.
The typeface (Lassigue D Mato) was chosen to be a script as a quote is a sometimes a quick quip, or something transitory, something this particular typeface epitomises.
The fading in colour of the arcs mainly is a fading of the intensity of the sound waves and was an aesthetic decision, as opposed to a symbolic one.
The colours are red, blue and green, representing the three primary colours of light, as well as the three colours that used for links on MediaWiki projects. The current default theme has changed the green links to a lighter shade of blue though, so it's mildly outdated.
In terms of the shape of the logo, the white space in the main circular area forms a stylised "w" representing "wiki". This, also allows the green area to represent a book, which is a symbol of knowledge. The blue arc surrounding the book hopefully represents "encompassing" that knowledge, which is something that the Wikimedia projects hope to do. The smaller red circle interrupts the blue arc, which can show the incomplete nature of a wiki. Completing the arc would imply that all knowledge has been encompassed, which is a practical impossibility. Serendipitously, the combination of all these elements also forms a humanoid, with the red circle being the head, the blue arc being arms and the book of knowledge being the heart/torso.
Due to the colours and typeface (Gill Sans) I chose for this design, they have now been adopted as the official colours and typeface for Wikimedia according to the Wikimedia visual identity guidelines.
If anyone wants more clarification or has any other questions, feel free to email admin (at) neolux (dot) com (dot) au.