So what ever happened with needling?

[Kendalizor]

  I remember it was a bigger issue a few years  back to where it was subject to penalty but I never saw anything about it in the TDA rules. I personally never could understand being offended by it but I know many still do and I've noticed it happens less often around me anyway.

[Luca P.]

I suppose it's a part of the game unless being rude or argue or insulting another player.
I remember of a WSOP quarrel between Friedman and Lisandro that you can find here:
http://www.youtube.com/watch?v=4yLF22lIuFQ

In this case for what I've seen, Friedman was needling Lisandro saying he robbed chips, but he went way out of line. Questioning someones integrity is a serious offence. Lisandro then started to threaten him, then the rest... well, it goes without saying.
Floorman intervened when Lisandro was about to knock him off the table lol