I am involved in the Blender (www.blender.org) community, and stuff like this happens fairly often.
People take the source, change any mention of blender in the program and change it into some other bit of software and sell it. Blender is GPL though, so this is entirely legal. Where they go wrong is by using art to advertise the software, with out permission from the artist, and claiming it was made using the renamed software, which it wasnt. so the images get taken down, they have nothing to advertise with, and after a few weeks the software disappears and everything returns to normal.