What's a good intermediate Ubuntu book?

[david-8uUts6sDVDvs2Lz0fTdYFQ at public.gmane.org]

I want to buy an Ubuntu book for a friend.  He's definitely not a
beginner.  He's also a Software Engineer, not a SysAdmin, so I would like
the slant to be more towards power user than admin.  And of course fairly
recent is good.

Any suggestions?

Thanks.