The package is offered "as-is" without any warranty or commitment to support. However, informal advice and help is available via the PEAR user mailing list and XML-RPC.com.
The PEAR user mailing list can be contacted for questions concerning the usage of the package. More details can be found here.
For more general XML-RPC questions, there is a Yahoo! Groups XML-RPC mailing list.
The XML-RPC.com discussion group is a useful place to get help with using XML-RPC. This group is also gatewayed into the Yahoo! Groups mailing list.
Complete details of the book are available from O'Reilly's web site.
Edd is responsible for the chapter on PHP, which includes a worked example of creating a forum server, and hooking it up the O'Reilly's Meerkat service in order to allow commenting on news stories from around the Web.
If you've benefitted from the effort he has put into writing this software, then please consider buying the book!