There have been several threads for the individual editions that were picked up, but I believe it would be good to put some things in order.
Currently as far as I know, these editions are actively maintained by community members:
Let me know if this list is incomplete or if you are also helping and I didn't acknowledge you.
Now, as far as I'm concerned, the MATE version can be rebuilt and uploaded as a semi-official edition. I believe the Multimedia is in a similar state or will be soon. I would like to ask for the core team's opinion on how these editions should be presented. After going through the cycle of tweaking some files, compiling image and testing it on hardware I can say that I'm comfortable enough to continue doing so, with a release cycle of at least twice a year (will be following the Ubuntu MATE releases ).
Lastly, this is a place for maintainers to share screenshots of their work so far! Here is MATE with the revamped icon theme: