The GSL may stand to being revised. Note this is an unconfirmed rumor floating around Enworld and other D&D sites (such as Necromancer Games). But there is an unconfirmed report that certain people have seen a draft copy of a revised GSL.
So, what is the GSL? Compared to the OGL, nothing short but Corporate bullying. It's one of the major reasons why I steer clear of D&D 4e.