I don’t know if users displaying library catalog rss feeds on their web pages is a very compelling argument for OPACS to generate feeds, I think figure of less than 1% of users wanting this is probably more like less than .00001%. I do think it is useful for some people to be less than enthusiastic about some of the things that library bloggers are salivating for, if only to force us to examine our assumptions.
I think I’d prefer to have RSS feeds coming out of a federated search product first. Heck, I’d be happy if I ever got e-mail notification from my public library, which I’ve signed up for 3 times. Or paper notification sent through the mail! Or a phone call! I’ve never gotten notices, even when I’ve had overdue books or holds waiting for me.