Will there be any? If so, will it be just like the Magic of Incarnum book, or a trigger event to fill the world with it, etc?
I believe the general decision in the beginning was to limit material to the core books. Besides, I find Incarnum to be rather niche-specific, and I've heard varying accounts of it's actual balance.
From what I've read the general consensus is Core/OGL, with a few things homebrewed. While this does deny us some of the nicer mechanics and flavor out there (Tome of Battle, Incarnum, Tome of Magic, etc..), it allows people that do not have these resources to join in on the coversations. for Example I do not have the Incarnum book and know nothing about it, so I would not be able to join in on any discussions about it.
doesn't Incarnum have a pretty steep learning curve?
Mustard and Crit are right though, the original plans were to keep things "cored." That could change though, we haven't really had people working on this in awhile.
Yeah, i agree with the niche thing and the learning curve..after recieving the book for my birthday i read through it twice and was still like, "Huh?"
Oh, I disagree on the learning curve - if you want help learning Incarnum, send me a PM, once its explained to you its pretty easy to grasp (it does need that initial explanation, though.)
However, I'm a big fan of keeping everything OGL, which is what the plan was when we last discussed it. I think it should stay that way, just because it would be all kinds of awesome to publish a CeBeGia book on LuLu or something once it's finished. :)