See also this blog, and the fact that they had an L. Ron Hubbard Stories from the Golden Age float at the recent annual Hollywood Santa Parade 2008.
PS - I find it remarkable that LRH significantly went into the science-fiction genre, departing somewhat from his more down-to-earth adventures he wrote previously, after his 1938 out-of-body experience where all the secrets of the universe were supposedly revealed to him. Maybe it's just coincidental circumstances but still.
This should be clear from this list.
Also, from http://www.cs.cmu.edu/~dst/Library/Shelf/atack/bs2-3.htm
"Writer A.E. van Vogt, an important figure in the early Dianetic movement, has said that Hubbard claimed his heart had stopped for six minutes during an operation, in 1938. Excalibur was the result of the revelation Hubbard had during this near death experience. Armstrong has said it was a dental extraction under nitrous oxide. Hubbard told his literary agent that a "smorgasbord" of knowledge had been laid out before him. ... In 1938, Hubbard became a science fiction writer, claiming he was "summoned" by the publishing firm of Street & Smith to write for Astounding Science Fiction. Hubbard protested that he wrote about people, not machines, and was told that this was precisely what was needed. ... Hubbard joined editor John Campbell's circle of friends, and became a major contributor to the reshaping of science fiction which Campbell brought about. ... Hubbard's interest in the occult continued, and for six months in 1940 he belonged to the Ancient and Mystical Order Rosae Crucis (AMORC)."Other interesting related links: