Nonetheless I thought you might find it interesting to know a bit about the ethical impact of them.
The verdict in short is, the latest model is having a better impact:
http://www.treehugger.com/files/2008/10/new-macbook-pro-whats-the-eco-impact-of-building-a-laptop-from-a-single-piece-of-aluminum.php
BUT obviously smelting alumnium in the first place isn't the friendliess process (remember basic chemistry lessons?) - are there alternatives? Yes is the answer get a bamboo computer which is of course made of biodegradeable elements - http://www.treehugger.com/files/2007/03/asus_bamboo_eco.php.
I wonder what the average life-span of these and other laptops is? And how many people do recycle their plastic, bamboo or aluminium laptops and PC's at the end? Sadly I don't think I ever have.