This begs the question...
Is it wise to put a back cover on the iPad or use it in a leather folio case? Would these not trap the heat and prevent proper dissipation? The user may not feel the warmth as much, but it could potentially cook the innards of the iPad.
In other words, if Apple designed the iPad to dissipate the heat via the aluminum shell, is it supposed to be only used naked?
That's a great question. I suspect that you could do damage to the internals if you trap the heat.
This is going to be a sad statement but...
Bottling up the heat with a cover might shorten the life of the electronics, but will probably get you through a year. Many if not most of us will sell the iPad 3 should there be an announcement of an iPad 4 next year. So those that buy a used iPad 3 come Jan-Mar 2013...as they say in the used car business, sale is "as is".
Then again might be a selling point in those ads if you say "used naked". Might get a different response though, nothing about buying a iPad.