Peter Hickman wrote:
> A Ruby cookbook would be nice.

Actually as a Perl programmer the Perl and ??? (XML, DBI, LWP etc) style 
  books are really useful. But I think getting such a single topic 
focused book out would be really hard for a less well established language.

However a Ruby and XML book could be put together as an edited work from 
several authors, possibly the module authors with an editor for consistency.

Looking to the O'Reilly Perl & XML book as a guide we have

10 chapters

1 - About Perl and XML and why Perl and XML
2 - Overview of XML and XML processing software
3 and 4 XML processing basics
5 SAX
6 Tree processing
7 DOM
8 XPath, XSLT and other stuff
9 RSS, SOAP etc
10 Coding XML

and only a little over a cm thick.

It's a can do if you can get the various authors involved, an editor and 
(of course) a publisher.