More stuff about the new 4e GSL has been revealed and it seems that companies who decide to support 4e can't continue to publish 3.x/OGL products. This is fine for companies like Necromancer Games who are going to publish 4th Edition D&D material only but rubbish for Green Ronin who have a very successful superhero game in Mutants & Masterminds and a simplified version of d20 in True20. It looks like these companies are going to have to make a tough decision to support their current lines or switch to 4e. More info (and a lot of outraged posters) here
There are also reports that publishers won't be able to continue selling things with the old d20 system logo on after a certain date. This will mean a lot of d20/3.x stock being offered at cheap prices to sell it off.