From what I understand it might still be illegal, the refs just don't call it. ESPN had a story on it a couple days ago which has since been updated once it became known that the Packers are the team that proposed banning it.
Mark Murphy apparently also did a Q&A on the Packers website and spoke about it saying:
Troy Vincent also mentions that the Tush Push play has been something that has been discussed at least twice in previous seasons so it's not like the Packers proposal is coming out of the blue, this has been a rule that is being continually examined.
Personally I think it should be banned. But on a scale of 1 to 10 of things I'd be passionate about seeing happen it's pretty low, like a 3 or 4. If they change it great, if not it's not going to bother me too much.