Unable to find a definitive answer to the question of copying the blockchain to another computer, I asked Gavin via email:
In Bitcoin-Qt 0.8+, how can the blockchain be copied from one computer to another? Is it simply a matter of copying the blocks and chainstate directories?
His reply:
Yes
That's right. I posted on this here:
https://bitcointalk.org/index.php?topic=157314.msg1680307#msg1680307Basically just make a copy of the whole Bitcoin data directory and drop it into any computer with the Bitcoin-Qt client installed on it. Make sure the client is not running and replace the existing directory with the copy.
BE CAREFUL NOT TO ERASE ANY WALLET THAT MAY HAVE VALUE!