I have been closely following the rumors thread on Warpshadow, and have been thinking about the nature of rumors with GW's latest policy. In past days we would already have the full listings, now it seems like we have to wait until stores get their copies. A couple of choice tidbits seem to make their way through, but a lot of those become fan speculation. Fan speculation becomes rumor and rumor becomes truth.
Here are the facts about the new Tyranids:
It was written by Robin Cruddace.
It will be released in January of 2010.
3 plastic models and 3 metal models will be released simultaneously.
The codex will have never-before-seen creatures.
There is a much circulated quote from Phil Kelly that says that there will be 4 new creatures. Since I have seen no official word on it other than a rumors thread over on BoLS I'm not counting it as truth.
That is all we know. The rest is rumor, hearsay and speculation. Some of the rumors may be truth. For example, it seems practically a given that there will be a plastic Trygon. However, there has been no official confirmation and even those who are in the know say that they don't know if it will actually be in the codex or if it will be an Apocalypse side-release. Other rumors of cheap gaunts seem very plausible, while others of 8 point Genestealers seem very far-fetched.
Finally, the last few pages of the Warpshadow rumors thread discuss what that big thing is in the background of the new codex cover. Many people think that whatever it is, it must be in the codex be it an Exocrine or some other monstrosity. Whatever it is, I must point out that Phantom Titans are depicted on the cover of the 4th edition Eldar codex, and yet that model is not found in the codex. I have tried twice now to register on the Warpshadow forums to point this out, but they haven't activated my account yet so I'm posting it here. To me, that giant spikey thing in the background isn't supposed to be anything other than a suggestion of a monstrous Tyranid horror.