Please take with a ton of salt.
Well, I recently found myself in a very interesting situation. Forgive me if I am sketchy on names, as I have no desire to put anyone in hot water just to bring rumours to a forum. I have been making the aquintance of a young Brit over the past several months. Recently, we met for the first time after having talked for some time over email. As we are both huge GW fans, naturally we began talking at length about 40k. At this point my new friend dropped a certain name--Hey, do you know ---- ----? To which I replied, "Yeah, of course I've been into GW for a long time". To my surprise, the gentleman told me that the aforementioned individual was, in fact, his brother. Now, let me just say this: If you know GW the company, and who the inner circle are, and in particular which people would know about products in development, then you too would know the name. Anyway, we proceeded to discuss the future of 40k and this is what I was told. Please keep in mind that Our conversation occured last weekend and I have had a very long week and I'm writing this on a commuter train.
1) The way projects are developed has changed a lot. The process now is that anyone within the group can pitch ideas for approval. I don't know when this became the way of things.
2) Chaos legions codex. Apparently, there will be rules for fielding forces from the various traitor legions. I've heard this rumour around before. He mentioned that part of the focus will be to highlight to differences between normal marines and warped chaos marines, both in the appearance of the model and in the organizational structure of the legion. If I recall correctly, he mentioned this as the first release of 6th edition. Also of note, Apparently a pitch to release traitor guard as a codex was put forward and rejected though the person pitching it put forth a very good proposal.
3) 6th Edition. He said it is just around the corner. I think he was more specific but I don't want to compromise this information with half remembered details. I believe he mentioned 2 codexs to be released before 6th. One was Necrons and the other was either Dark Angels or Eldar. I was surprised at this. Whatever the order was (either DA or Eldar, the other will be the second book in 6th--damn it, I can't remember which one!)
3) The boxed set for 6th with be Chaos versus Dark Angels.
4) I really wanted to get news about the Tau. Heartbreakingly he said that the Tau are not even being talked about at this point. They are way out in the lineup.