already mentioned Sandy Petersen's excellent panel about Gloranthan secrets, called “Elder Secrets of Glorantha”, that I had the privilege to attend during last year's The Kraken convention, er, gaming vacation. I believe that much of the information divulged by Sandy at his panel was quite novel.
Well, Fabian Küchler has made the transcript available as a ‘chapbook’, i.e., a fundraiser booklet for The Kraken. The PDF will probably be publicly on sale, but the dead tree version is only going to be available for attendees; it will have art by Jon Hodgson and be a limited and numbered print run.
If you want to pre-order a print copy of this chapbook, write to fabian [at] the-kraken [dot] de. More information here.