After some advice.
I have a client wishing to have an app which lets them download a voucher to redeem in store but only after they post details of this offer onto 5 friends' walls.
My understanding of current Facebook policy suggests that:
1) Promotions can't require users to take any action on Facebook other than to like the page (likegate);
2) Messages posted to multiple friends at once should be unique and personally initiated - i.e. an app shouldn't bulk post to multiple users. Instead users should share things on their own wall....
Am I correct in this understanding? If so, can anyone point me at the relevant facebook policies - can't seem to find them on the site.
Yes, those are exactly what I read on the policies page. However to be absolutely sure, you should have your corporate attorney read them and consult with you.
See http://developers.facebook.com/policy/ and http://www.facebook.com/promotions_guidelines.php