On both my pismo and my tibook, I did get heat through the keyboard, but not enough to kill the LCD, but I still had mine operating partially or fully open, even in external-only mode, as seen here: http://ueberwiki.hopto.org/index.php/Image:Anotherolddesk.jpg and here: http://ueberwiki.hopto.org/index.php/Image:Pic06032.jpg

It's only ever useful if the LCD dies.
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