Cel-Ray sounds like there would be radium in it or was once upon a time, but it's just a name for a celery soda. jmaynard brought me a bottle (from the same place that has the Walnetto) and I'm drinking it now. Jay doesn't think much of the soda as it tastes like celery, a flavor he does not appreciate.
I expected it to be, well, weird. The flavor is from "extract of celery seed" which makes sense. The flavor is rather concentrated in the seeds and it's how celery salt works. I tried it and found that I like it, rather to Jay's chagrin. The bottle cap is marked "kosher for passover" so this was made with proper sugar and not corn syrup.
Upon seeing that some consider Cel-Ray the ideal accompaniment to saltier foods such as pastrami, I find I now have a desire for something I will not get in Fairmont: a really good pastrami sandwich. And I'd need another bottle of Cel-Ray to go with it.