Thank you Peter and Fred for your gracious and thoughtful responses. We can group-hug later. :-)
To business...
"[i]Theremins are popular instruments among avant-garde and new music artists because of their perceived freedom from traditional compositional structures. It is also performed as a classical instrument, and is occasionally used in jazz improvisation.[/i]"
As the rest of the article is taking a chronological structure, I think it would be consistent to list the various uses in similar order.
My understanding is that Lev primarily intended it as a classical instrument, and this is certainly the way the RCA theremin was promoted, as well as being the use that the first highly prominent thereminist, Clara Rockmore, made of it.
After classical I would mention avant garde, as it soon attracted the interest of some avant garde composers of the time. Then I would mention it's use in film scores, particularly in science fiction and terror. (i.e The Day The Earth Stood Still and Spellbound, - Hoffman and more recently several others, most notably Lydia Kavina, but other notables too,) and as a novelty instrument - Hoffman (and Musaire in the UK) were both variety acts, and more recently comedian Bill Bailey.
Then occasional usage in pop and rock. Lothar and the Hand People, Led Zep, Capt. Beefheart (Hoffman played on "Electricity") and The Bonzo Dog Doo Dah Band.
And more recently adoption by the electronica and experimental etc. subcultures. notable examples might include The Lothars, Add N To (X), Eric Ross.
I'm not entirely sure when jazz fits into the chronology, improvised or lounge. (i.e. recently Pamelia Kurstin and Robby Virus of The Pimento Project to name one of each.)
Here's a blurry line. Does an artist who uses a theremin in a piece of performance art, or an installation, count as a thereminist? If so, then a recent notable example of a theremin installation artist would be Ray Lee. Possibly early in the chronology - e.g. the terpsitone.
As for including people who are visible on internet forums, etc. I didn't think that qualified. Generally my understanding is that, for the purposes of the article, being well known amongst thereminists is not considered as notability.
Neither (if you had me in mind) do I think that I qualify as a published artist - one iTunes only album, not a major label, and one article in a Portuguese based fashion magazine with a few distributors in London, New York etc (http://www.zootmag.com/) is not what I consider "notable."
I would however, like to see mention of Theremin Festivals somewhere. The two largest were The First International Theremin Festival, in Portland, Maine in 1997, and Hands Off 2007 (*), ten years later, in Bushey, England, both with around 50 attendees. It seems likely that the Portland event was reported on, and I have - somewhere (I have not so much a filing system as a fire hazard) - a copy of The Wire magazine, (http://www.thewire.co.uk/ - distributed through major newsagent chains throughout the UK) with an article covering Hands Off that name-drops a few thereminists.
Joe, digging out back issues will take some effort, so I'll only do it if you consider it important.
(*) I declare an interest in Hands Off.
Thread continued here (http://www.thereminworld.com/forum.asp?F=1&T=4130&cmd=p&p=1).