The Game System License (or GSL) for 4th Edition was posted up today and after going through it.... wow. It is really restrictive.
Thinking back on a number of my 3rd Party OGL products, I do not think very many of them could have been published under this license as they currently stand.
Lets take a look..
Liberation of Prince Thorgrim, Compleat Encounter - Nope, includes miniatures. (GSL, Sec 5.5)
Critical Hit Deck - Nope, as it redefines what a critical hit is. (GSL, Sec 4.1) I might be able to get away with the fumble deck.. maybe.
D0: Hollow’s Last Hope, GameMastery Module - Nope, includes page references in the MM. (per the FAQ) and reprints monster elements (GSL, Sec 5.6)
W1: Conquest of the Bloodsworn Vale, GameMastery Module - Nope, same reasons as Hollow's Last Hope. This actually goes for all of my adventures...
Classic Monster's Revisited - Nope, reprints monster stat blocks. Alters core monster stat blocks. (GSL, Sec 5.6)
Pathfinder Chronicles Gazetteer - Hmm, this one I might actually be able to publish. Maybe, except for that the entire Pathfinder line would also have to convert, and almost all of those would be in serious breach. (GSL, Sec 6.1)
And last, but certainly not least...
Pathfinder RPG - Yeah, this one is in breach in just about every way that a product can be in breach. It includes rules for character advancement (GSL, Sec 5.5 (b)), reprints rules elements (GSL, Sec 5.6), and includes open content, which the GSL has no provisions for.
There is some crazy stuff in that contract. It can be killed with basically no notice, and if it is, you must destroy your stock. If you put out a monster (or class, or feat, or whatever), and Wotc later puts their version of that rules element into the game and the SRD, your product is in breach (as far as I can tell). There are no demons or devils (along with a host of other classic D&D monsters) in the SRD (goodbye 4E Vrock.. I'll miss you), nor are their any of the higher level character options (paragon paths, epic destinies).
Now, I am not a lawyer, and this is just my personal read through of the document. That said, it sure seems to me like Wotc wants folks to play in their sandbox, so long as you stay in your corner, do not touch any of their cool toys, and don't make any sandcastles that compete with theirs.
Or maybe that is just me. Man am I glad we stuck with the 3.5 OGL.
Edit: The folks on the paizo board, especially the estemed lemuriapress, brought this up concerning the license.. it is too good for me to pass up.