book recommendation for Python newbie?

[Joe Strout]

I'm trying to (gently) convince my business partner that we should be  
adding Python to our core toolset.  He's never used it before, apart  
from poking around in the tutorial a bit at my urging.  But he's got a  
birthday coming up, and I'd like to get him a book that will help him  
make the transition more smoothly and enjoyably.

In case it matters: his background is mainly in databases (originally  
4D, more recently MySQL), and his current primary tools are REALbasic  
(which is a statically typed language with semantics similar to Java)  
and PHP.  He's primarily a Mac user, but occasionally has to dabble in  
Linux or Windows.  If we do make this change, he'll be using Python in  
a professional capacity to develop commercial apps.

There are a lot of Python books out there... which one would you  
recommend in this case?

Thanks,
- Joe