I just implemented a "Discuss" feature in CAREO, that will let you (or anyone else) discuss a learning object. Currently, it's quite simple (by choice, after taking to heart some of Joel's thoughts).
It allows threaded discussions, sorted by date, and anonymous posting (we're going to be using it for K-12 stuff, so we can't make tracking user info mandatory).
Head on over to http://careo.ucalgary.ca and try it out.
It's a bit quirky at the moment (like when you save a post, it takes you back to the main menu. It shouldn't do that. I know that. I'll fix that ASAP - but it WORKS!).
I was going to implement a tie-in to something like WebCrossing, but decided I could do a "liter" more integrated version myself.
It took less than 6 hours to design, prototype, implement, and deploy. Man, I LOVE WebObjects!