People see stuff on forums because they want to.
People see stuff on Facebook because they are under the impression that they have to (aka they aren't sure how to use it). I like to take advantage of that.
Beside, it's without a doubt the best way to stay in touch with what your friends are up to, on your own time, without actually having to interact with them....
...and you can totally judge the chicks your friends date.
Mainly, I want to be able to post something about the store in one spot and feel confident that lots of possibly interested eyes will see it. Our Facebook stats are really interesting, and the correlation between the number of views a thread on the boards gets within 24 hours and posting it on Facebook is interesting as well.
People these days rely on Facebook to keep them in the know. If it's not on Facebook, it's not really happening. (And you'd be horrified how true that is)