A while back (It looks like 2012ish), I think before MakerBot bought Thingiverse, Thingiverse changed their Terms of Service/Use (ToS/ToU) and The Internets were up in arms about it, claiming that the owners wanted to steal the work from creators. It went so far that people were posting text explanations protesting in their projects in an attempt to raise awareness of the change.
This link attempts to address the phenomenon, and is written by one of Thingiverse's lawyers. Their current ToS have the legalese on one aside, and an attempt at plain English on the right (A great idea).
I'm not a lawyer, nor do I really have access to one. I would like to design and post things to share, much in the same manner as Thingiverse. I believe GrabCAD makes a point of saying that they will not try to steal or take your work from you in clear text when you sign up, as if it were a feature.
What can Thingiverse do with my Things according to their Terms? Am I potentially signing away something I would probably regret if I decided to try to monetize on something later?