Update (5/31/09) - as Glen notes in the below comment, you can order the book through an English language site. Please seen the instructions in on his blog (http://www.software-smith.com/csbook.html) or go directly here for the site (still a little German, but it’s easier to follow in English).
The first – and only – book on Commerce Server 2007 is now available! (Here’s the translated version, thanks to Microsoft Translator - http://bit.ly/Gfm7R; note that you cannot purchase the book when using translator.)
Unfortunately, the only location you can currently purchase the book is from Amazon.de – not sure why it’s not available at Amazon.com, but hopefully this gets resolved soon. I can assure you that this is an English version, and not German.
That aside, I really hope you find this a useful book. It’s been a longtime coming, but it’s here now! Go buy it! If you have any issues purchasing this book, please let me know ASAP.