I did get a chance to talk to him -- for about 3 minutes.

He's aware of the fact that he's suffering from "can't-say-no-itis" and that he is struggling with having to tell people that he can't just magically respond to any and every noise someone makes within 5 seconds. Part of that is going to be part of an overall cultural shift in which the department itself starts standing up for itself better and stops caving in to other departments whining that they "caaaaannn't" do this or that and we end up doing their work for them.
I did get the go-ahead to schedule 30 minutes early in the week for a "catch-up" session. I also got the blessing to "go ahead and be rude if you have to to get my attention. I know that's going to be uncomfortable for you, but sometimes that's what I need." Well, okay, he's honest! I also downloaded an Access template ("Issue tracking" I think it was titled) and adapted it so I can run a report showing what's still open that needs his reposnse. So, in general I feel better that there's been some honest acknowledgement of the issue and some baby steps toward improving things.
The other thing is that it turns out I'm not the only one in the department with this issue, and Boss addressed that in the staff meeting. He acknowledged that this year, things have been in a state of flux and that hopefully we'll be settling down soon. EVERYONE'S apple cart has been a little upset in one way or another this year. So it's not just me.