I had a surprisingly hard time figuring out how to do this; I had to carefully read some posts in the "Google Reader" Facebook page (Peter explained it to me, but I didn't get it). Judging from those posts, I'm not the only one flailing about. The trick is the "settings" button beneath the "Write something" field on the "Wall". If you click it it a new area appears as below ...
d my Google Reader Shared Items web page and copy/pasted that URL.
Update 3/30/09: Uh-oh. The setup seems fine, but nothing I share is appearing on Facebook.
Update 3/30/09b: Another set showed up. Maybe it updates once daily? That would be fine.
Update 4/19/09: It started updating several times a day, which was much too high a volume for my friends. I had to turn it off. The update behavior seemed unpredictable.
Update 4/25/10: I decided I'd try this again but link Facebook to a single blog. Alas, it looks like this feature was discontinued. I don't think there's a way to do this without an app of some kind. The most recent summary I could find on this topic was posted in mashable.com August 2009, but even that is out of date.
Facebook is all about lockin, so this type of functionality is going to be fragile. I suspect most vendors have given up. Twitter, for all of the things about it that truly annoy me, is not a lock in solution. (So sad that Google mangled Buzz.)
Looking around a bit, it feels like the action is in mashup services that deliver interconnection. One of these is "twitter feed", it connects any valid feed to a publishing service and it supports OpenID and OAuth -- so I don't need to give them my personal credentials. I'm going to look at what I can do with this.
Update 4/26/10: I did an update on this topic using the twitterfeed service alternative.