Maybe the definitive answer...
A bit of weirdness. One of our two laptops has been experiencing random shutdowns, so we brought it into the largest apple retailer in the country. While I was there, I checked out the MacBook Pro on display -- and guess what -- it, just like ours in our apartment, gave a buzzing to the fingertips as you passed over it. I asked the sales rep if this was normal -- he claimed not to feel it. An eight year old kid was playing with an iBook and told me it was normal, for MBPs. Another sales clerk agreed, explaining that you "have energy in your body." Which is really funny, when you think about it.
Perhaps the reason more people aren't reporting this problem is that people in countries with certain voltage levels don't realize that it's not supposed to be like this. The salespeople acknowledged that major electrical shocks were a bad sign; we've had some minor ones from both of ours; but there was apparently nothing unusual about the release of a good deal of electricity from the skins of the laptops. Of course, this never happened under 110V in North America.
The salesman also asked if, when we plug in our adapters, we see a major, fiery spark from the outlet. We told him yes. He explained that this was a sign that the Apple adapter was properly switching over to 220V power. Funny; we thought it was a sign we were about to burn down our apartment and roast our logic boards...
Seems like maybe nobody from Apple has gone to test their equipment in South America.