Indeed 
It is sixth edition and it will all be released at once. They're going to hire a dozen writers /designers to go through every post in this forum and everywhere else fifth edition has been mentioned, they're going to decide on a whole new slew of mechanics changes to resolve every problem anyone has ever mentioned about fifth edition. Then they're going to re-edit all of the fifth edition books with the revised mechanics and killer organization as a $500 seven volume set (with a pdf version available for $350, $20 if you purchase a hardcover edition as well.)
Automated Ars Magica forums post generator!
No need for us to write them anymore. Just log on and enjoy :mrgreen:
I can't believe no one has yet suggested: Ars Magica, the computer game. There will be an iphone/android turn-based rpg, and an playstation/xbox/computer MMORG.
I'd be happy with an app that just does Certamen. 
Does this mean, for the first time ever, a Diedne source book?
If the video game funds successfully through Kickstarter -- yes, the budget involves creation of the official Diedne sourcebook for the tabletop RPG, per the rewards for various support levels.
Sweet!
Please, no. Some things are better left mysteries.
Looks like I got my Certamen app, and then some!
I've always been open to the idea of a source book that has three or more mutually incompatible takes on them. The idea of a definite take on them in canon upsets the crotchety old old fart in me, but not any more than the present take on house Tytalus (which I'm not as fond of as the Tytalus in prior editions).
So while some things are perhaps better left mysteries, I'm cautiously optimistic anyway taking the bad with the good.
Does having guessed correctly win me a free copy? 
Doesn't matter, I'd support the kickstarter anyway. I'm very poor, but Ars is my favorite place to put what discretionary cash I do have.
No, you were too slow. 
The video game starts in 1000 AD, before the Schism War, so you can play the Diedne. A sourcebook rather becomes necessary. We need full details of Diedne magic, for example. On the other hand, you don't get to play the leadership of the Schism War, so we won't be defining everything about who was right and who was wrong, as the description for the Kickstarter says.
The sourcebook will include a section on how to use the Diedne in 1220, and that will be options: Legends of Hermes/Ancient Magic type stuff, a couple of return of the Diedne options, maybe something else. Unlike every other case, this book has, of necessity, been announced before we've really started working on it, so the contents could change, but those are the current plans.
And the World Book? Is that more of a computer game guide, like the Players Guide for Skyrim or Dishonoured, or is it a tabletop game book?
Will this book be available outside the kickstarter project in any format (hard cover, soft cover, .pdf)?
Same question for the world book.
We don't know yet. I'd like it to be a tabletop game book: Stonehenge 1000 for ArM5. That will depend a bit on how close to tabletop canon the computer game can be kept. The world book is a bit open for development yet, depending on what seems most useful given the way the project goes. It is, however, likely to be useful for both the computer game and tabletop game.
If the Kickstarter doesn't fund, neither book will be available at all.
The Collector's and hardcover editions will definitely not be available outside the Kickstarter project. Softcover reprints at some point in the future are a possibility, as are PDF sales, but not for some time after the computer game releases, and possibly not at all; that's something we haven't decided on yet. After all, the Kickstarter hasn't funded yet.
I'd love to help fund it, but I really don't see myself being able to afford (the rather steep) $150 before the end of November to get my hands on the hardcover Diedne sourcebook.