Keep in mind these are ultimately rumors and not necessarily true.
The information was originally retrieved here.
Here are the rumors:
Lorizael on Dakka Dakka
My sources say this will be a 70 page "compendium".
It will have updated 6th edition rules for flyers:
Stormraven (now available to space marines and BT)
Storm Talon
Ork Bomba / dakka jet / burna bomba
Valkyrie / vendetta
Razorwing & Void Raven
Night Scythe / doom scythe
Also dog fighting rules from crusade of fire and a new flyers scenario. I'm told this book will be a range item and not a limited release.
DarkWarrior1981 on Warseer
This is not as exciting as people may think. I saw the advert for the book at a local store; It contains only rules for fliers still on sale or with a codex entry (the Dark Eldar bomber is in), some fliers have their rules updated to 6th edition (whatever this means exactly). The only thing actually new is, that the Stormraven is now available to Codex Space Marines and Black Templars as well. Also you will find the flier rules from Crusade of Fire and new missions. The book will be on sale (no pre-order) from 16th of February, is direct only (so not from your FLGS), english language only and will not be limited stock.
Now, I know that we have all been struggling with dealing with enemy flyers in our respective bike armies. Therefore, this will vastly expand the capability of our armies to be competitive in tournament scenarios. Another interesting note is that the Helldrake and the New Dark Angels flyers are not included in this supplement. Perhaps the units which are included are going to be getting more expensive or have stat changes. We may even be lucky and see the storm talon become cheaper so it is more useable! Maybe this will usher in a new era of less flyers?
At any rate, is this a welcome change? What do you expect to see? Would use use a Storm Raven in your army?