Interesting info - it isn't often that Google clarify anything when it comes to AdSense. So I guess it's okay to recommend referral products as long as you don't blatantly say 'Click here now and download'.
Darn.. you beat me to it... I've pretty much posted this (almost word for word) over the last few months. I've spoken with Dan Friedman (he's the Adsense team member that made the post) a few times over the last few months and he had explained this all to me.. like i said, i've posted it piece by piece here but who's gunna believe me? I'm glad they "officially" let everybody know - being able to fully endorse your referrals will greatly increase your earnings.