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).
The d20-licensed products always felt more than a little awkward to me, it was a pain to have to puzzle through the cryptic references to the Players Handbook, and the greatest innovations in this segment of the game industry came from those who decided to go with a full Open Gaming License-based product, divorcing themselves from D&D entirely. While Hasbro's suits may view this lack of direct connections as a bad thing, I think ultimately it achieved exactly what the OGL was supposed to achieve: namely getting everyone to play some derivative of D&D 3.5.
Now yes, the downside was the it gave rise to such loyalty to the older edition that Paizo's Pathfinder RPG was spawned, but it seems to me that's exactly the sort of loyalty you want to inspire amongst your 4E converts.
Having said that, even having a D&D license that requires people to use the Player's Handbook as a core book could be a good thing -- given the amount of people upset by the MMORPG direction that D&D is taking with 4th Edition, I could easily see someone (Necromancer Games perhaps?) releasing supplements aimed to restore the classical fantasy feel to the game.