Oz, I completely agree with you, and wanted to post the same thoughts (though not in such eloquence ).
Reading Bible examples of excomunication shows to me that is exactly what the Bible is saying to do too. Every Christian has his own conscience, and I don't need a church to enforce the shunning, the person HappyGuy described would have been shunned by me anyway, religion or not.
Edited to add: to reach a proper conclusion regarding my choice of shunning someone would need a proper flow of information too, meaning when asked, elders (or priests, or whatever) should tell me openly what was his fault. A generic "X Y is no longer a J W" will not do it.