I have no idea why. But apple have not earthed the stubbly plug for the macbook pro transformer. So on the short lead the only way the charger is earthed is when I touch it or the macs unibody which gives you a sort of vibrating feeling on your palms.
When I went to the genius bar to complain about it they said that it was completely 'normal'. Where their definition of normal is that every MacBook does it. I have had 4 MacBooks and all have done it.
The genius did say that he though he has seen a few earthed 3pin plugs. So my question is where can I pick one up? or how could we force apple to earth the stubby plugs and recall them? /nochance