However, cap60552 has hacked together a somewhat intriguing use of it, and I must give him props for this: Tweets from the library -- Sending "What have people recently borrowed from my library?" posts to the feed, and the ability to auto-post bibliographic data from his library's catalog (with a link to the catalog) to your own Twitter feed if you come across something you want to tell folks about.
He's now also added a daily tweet for how much paper the library's printers have used, in both pages and miles.
You can view his library's Twitter feed here.
(Also, on a complete tangent, be sure to check out the Halloween display he does in his yard every year.)
Of course, "Here's what someone just checked out" has the down side of "No, you can't have it! NOT YOURS! MWAHAHAHAHAHA!", but as he mentions, at an college library, a "Here's what was recently returned" feed would be empty for most of the year, and then get flooded around finals.
What's next--a "Here's what was recently withdrawn" feed so you know when to hit the library's used book sale or go dumpster diving?
Feudalism: Serf & Turf