Yes, there's something about it here:
http://theremincenter.org/ru/Projects/ThereminPark/index.html
That page is in Russian, so rather hard for most of us to decipher. It just so happens I brought this page to my Russian teacher (I take lessons, and am pretty much a beginner) yesterday, and she helped me read it.
It's in Moscow. It's an exhibition called Theremin Park, and is put on by "Theremin Center," which is associated with the Moscow Conservatory. There are electronic instruments invented by 5 different engineers including Lev Theremin; there are 6 composers mentioned of the music, including Lydia Kavina; and 8 thereminists mentioned who perform demonstrations on theremins at the exhibition.
Also, it says that the audience does indeed affect the sound in the room, which is called "poetry booth," but I'm told the word "poetry" in Russian has a broader meaning than in English to include other types of sounds too. "Booth" is a pretty inaccurate translation too, probably, seems that word also has an expanded meaning.
I don't see any date listed for it, wonder if it is ongoing. The 1992 year you see there is when the Theremin Center was founded.