The focal question in your previous post seemed to be At what point, exactly, do I cross the line on what I say?. That is an impossible question to answer. Libel and slander and parody and indeed abusive verbiage cannot be unambiguously defined, they need to be seen in context, and yes, a lot of that is and will (especially when concerning online behaviour) be tackled in common law. That is an ongoing process, but will never lead to a nice leaflet of bullet points to guide one through lilfe. One needs to be a fairly abusive person however to cross enough gray area in order to go to jail. So, it is not about crossing a line, it is about crossing a sufficient amount of gray area. Similar arguments can be made regarding stalking. When is behaviour stalking? There is no straight answer. And no, you would never go to jail for saying that Clegg is a bastard. On Slashdot there seems to be a sentiment that any repercussions following from abusive online behaviour somehow represent an assault on free speech. It seems to be a geek impediment of all-or-nothing binary thinking. I am not equating your post with this view, but it ties in with the gray areas. It is OK to protest/get angry/slam/mock/whatnot online. But downright abusiveness and targeted bullying is not.
As an aside, my remark "how hard is that grasp" did not contribute to the debate - apology.