I wouldn't talk about songs that are in Playtest if they haven't been announced somewhere on a band's or author's web site, for the reason stated above: a song could be "abandoned" by its author or perhaps a legal issue could come up that makes a song not allowable on the RBN.
The list of approved songs which I'm maintaining in the other thread is a bit different, since those songs technically are up on the Marketplace, just not viewable or purchasable until HMX flips the switch on the RBN store. HMX does have the ability to "un-publish" a song, but that would only happen in extremely rare circumstances.
There are a few on that list that I don't believe have been mentioned anywhere outside of the Creators site. If an author were to PM me asking me to remove a song from the list because they wanted to keep it under wraps for whatever reason I would have no problem with that.