Hi Vicky,
Thank you for all these interesting questions. I’ll try to answer and make things as clear as possible.
First of all, this work is one of the action of the Marketing Committee for 2018. I released it a bit late, and this is still a work in progress.
It has not been yet ‘approved’ by Mark’comm nor merged to the OSGeo Github branding repo. Some additional arrangements are needed, so better not to use it in ‘production’ for now 
I know the time it takes to do a design, as I do the release tweets designs for pgRouting.
Maybe I don’t understand the difference with the words symbols and logo. Can you explain your understanding?
Logo belongs to each project, has its own a story and involved most of the time specific design work by project contributors.
Symbols or glyphs are simplified shapes that everyone can remember easily and that can possibly scale at ‘any’ size.
From my perspective:
The majority of the projects symbol/logos look like their original design but they lost their color and they “look” gray (or is the gray green in the guidelines).
The goal of the symbol set is to gather all the projects logos in a symbol collection that can be used as a webfont.
One would basically import the CSS and then just write to make it appear in any web document, in any color, at any size or screen resolution.
I used one of the OSGeo grey color in the demo page you are right, but one is free to use any other.
if a project has its own logo/symbol, like, pgRouting, baby elephant playing with a compass, full with colors, is there a reason for us to have a design change, a gray elephant head with two triangles in the ear?
Once again, logo belongs to each project and i wouldn’t pretend to change any of them.
As for PostGIS Slonik, your elephant was difficult to transform as a simple symbol shape, so i decided to create a simpler one. I feel sorry if that is hurting you or your
community. Please note that i’m still at taming those two rebel elephants, so things should be much better shortly
Do the projects PSC need to vote for their logo/symbol change or is the marketing committee, from now on be in charge of the logo/symbol designs of projects and the projects PSC have no vote on that?
Oh no ! Not at All ! Nobody wants to change any logo, just get a useful SVG symbols collection to represent OSGeo projects in a simpler way when needed.
As SAC member:
Website:
Can you explain where in the website the projects’s symbol/logo would be used
If applicable: where the original logos would be used?
Where/how would the OSGeo foundation symbols set would be used.
Where/how would the initiatives symbols set would be used.
I believe each symbol could be used on related page as subtitles icons, as decorative html elements, as div or page repetitive background, or as images fallback when needed on mobile, or even in the OSGeoLive submenus or docs, as Cameron suggested.
These are only ideas. You should probably see this symbol set a basic resource for websites, prints or any other media where using the official project logo is not mandatory.
Wiki:
In the wiki page we have badges for example:
https://wiki.osgeo.org/wiki/File:OSGeo_PSC.png
We are still using the old logo badges, because there is no specification on the guidelines of how a badge should look like.
Good point, some of the symbols could replace some of the old badges. I didn’t think of it yet.
It is planned to integrate the symbols set in our branding assets, so its use will be eventually documented in the style guide.
I hope i answered your question and will let you know when the PgRouting symbol will be better.
Best,
Nick
