More relevant to the initial topic of the thread, I found this interesting reference while searching online.
Marjanen, Antti. “A Nag Hammadi Contribution to the Discussion about the Pronunciation of the Tetragrammaton.” Pages 153-160 in Verbum et Calamus: Semitic and Related Studies in Honour of the Sixtieth Birthday of Professor Tapani Harviainen Edited by H: Juusola, J. Laulainen, and H. Palva. Studia Orientalia 99. Helsinki: The Finnish Oriental Society, 2004.
Sadly I don't have access to an academic library any more so I can't read it. But others who can locate it might find it interesting to pursue. I have got no idea what its conclusions are.
Narkissos you raise the question whether the use of the transliterated form IAW in the Leviticus fragment indicates Jews were pronouncing the name outside esoteric and magical contexts. But I would have thought that the presence of the divine name in this form in the sacred text, (rather than on an amulet or part of some incantation) which is evidently intended to be pronounced, (that's the point of a transliteration) shows quite simply that, for those Jews who used this text at least, pronouncing the divine name during readings of the sacred text was routine.
I found this reference and summary online of what appears to be a PhD thesis submitted to the University of Cincinnati that discusses evidence for the non-mystical use of this form of the divine name. It looks absolutely fascinating. I wish there was some way of accessing it!
http://liaisons.drc.ohiolink.edu/handle/2374.OX/9377
And on the question of whether copies of the LXX that Philo consulted used the divine name I found this discussion interesting.
http://books.google.co.uk/books?id=TxZK1Le1DpkC&pg=RA1-PA122&lpg=RA1-PA122&dq=george+howard+tetragram&source=bl&ots=CU0Lu6qVkz&sig=4hyixHcs84eCvDRjBny5dBRrcNg&hl=en&ei=YpfqSePNCpeSjAfTjZyfCg&sa=X&oi=book_result&ct=result&resnum=10#PRA1-PA120,M1
I have been searching high and low in my files for my copy of George Howard's article, but I can't find it anywhere. However I did come across a copy I made of this interesting article about the importance of the divine name in early Christianity:
http://www.jstor.org/pss/1584631
Contrary to George Howard, Charles Gieschen agrees with Pietersma that kyrios replaced the divine name in the pre-Christian LXX. He argues that, although absent from the sacred text, early Christians were still very conscious of the divine name, and it continued to play an important part in Christology well into the second century. He cites contextual evidence from Jewish literature, then looks at the NT itself as well as other early Christian writings. The result of the analysis is a very high Christology among the first Christians who saw Jesus as possessing God's own name.