Wizards of the Coast has announced the D&D 4th Edition Game System License. This license replaces the old d20 license, and appears to take a different tact from D&D 3.x's Open Gaming License. Exactly how different is hard to tell from the announcement; if nothing else what used to be separate procedures and policies for d20 licensing vs. OGL licensing seem to have been combined into one set of rules.

Exactly what these new rules will allow you to do isn't spelled out -- the press release says it will let companies create fantasy-based games based on the 4E ruleset, and spell out what rules can be used in their games, but it doesn't say what rules can't be used. Which makes me wonder if we'll see the old d20 hamstringing carried over to the new edition (namely, if you want the d20 logo, then you have to rely on the core rules for leveling up characters, gaining experience, etc., as opposed to using the OGL, which lost you the logo, but let you create a self-contained games).