I found this interesting.
This morning, I sent a message within FaceBook to a pal of mine.
In it, I linked one of my client's flickr sets.
What I noticed was; that as well as sending my friend my message and link, FaceBook also appended the equivalent of a classified ad, (remember them) at the end of my message.
I can't decide whether that's cool,intrusive or naughty.
On balance, I'd go with the first.
My guess, is that this is FaceBook's take on the Google sponsored links behemoth.
And I wonder if it's part of the FaceBook plan to sell brand keywords to all comers, to tag along with a users sent messages?
Or am I just showing how little I actually know about FaceBook?