Hmm, if I am not mistaken they are soon to release a totally free modding membership, which will basically means access some (most ?) of the source code to modders.
Also, I'd be curious to know your sources regarding these infos (particularly the "notch isn't very happy about it" part). You say "our channels of communication", are you somehow involved with Bukkit or Bravo ?
The source code will be shared source, not open source; it will not be something which people can freely redistribute.
I wrote Bravo. One of my big supporters is a guy who has been involved with Mojang's inner workings for a long time, and who has told many a horror story about the inner circles of MC communities. (Name withheld for privacy reasons.) There are Mojang employees, like mollstam (the webmaster), chilling in our IRC channel, but we're really not able to get much information transferred back and forth. Things like on-the-wire exploits and data leaks aren't received by upstream in a reasonable timeframe, which makes it painful to do good security.
Actually, it's here : http://notch.tumblr.com/post/4955141617/the-plan-for-mods
Also, I'd be curious to know your sources regarding these infos (particularly the "notch isn't very happy about it" part). You say "our channels of communication", are you somehow involved with Bukkit or Bravo ?