Did a search at Amazon.com
There are plenty of books on Photoshop CS3, some in stock but most for pre-order, by various authors, namely, Scott Kelby, Martin Evening, Ben Willmore and Bruce Fraser.
http://www.amazon.com/s/ref=sr_nr_i...hop cs3&rh=i:aps,k:photoshop cs3,i:stripbooks
Should be also able to order through the larger bookshop here. Can also check with Riceball.