A while back, ThemeForest announced that it now has a completely GPL license option available. This does not mean that all of their themes are GPL, but it does mean that authors have to option to make their themes GPL.
This aligns with WordPress.org’s movement towards all of it’s themes listed being licensed under the same license of WordPress.
As a cool side note, WooThemes is now listing their sites on ThemeForest.
WordPress Educator Zac Gordon 