I received two job emails today.
One was a reply to the email that I sent yesterday to the friend-of-a-co-worker at the New England Journal of Medicine. She said she passed the resume along to the managing editor, and I found out that they are looking to fill two positions. She also said that she would let me know if she heard anything.
The other was from O'Reilly (!). Definitely not expecting to hear from them again. It was a nice letter explaining that they had chosen someone else. My "resume and experience were impressive", and they felt that I was a "great candidate for the position." They ended up hiring someone with previous book production experience. It's good to hear, actually. I feel satisfied with the O'Reilly experience now.