EDIT: Memorial service details (Sunday, 23 January, 6pm) are in a follow-up comment.
Michael was in charge of the LASFS library for many years. Not a trained librarian, he did what he could, and he had a love for the LASFS Library nonetheless. LASFS used to purchase its NESFA Press books by way of Bruce Pelz, and when Bruce died Michael Mason joined NESFA expressly to continue that arrangement. Now who will buy our books?
Michael was a habitual Worldcon attendee, and his collection of Worldcon t-shirts was one he was proud of. He had enough to wear a clean Worldcon t-shirt every day. He chaired Loscon a year ago, and "helped" with the Loscon program most recently.
He was also one of the people I'd talked TAFF strategy with, and helped me convince myself I wanted to run.