It seems that Yahoo! has posted their latest effort to help developers of web applications world-wide - the Yahoo! PHP Developer Center
There are already several links to articles (HowTos on creating REST web services) and links to other code examples using the service. Along with this release, they also note that:
...many of their web services now return serialized PHP
(developer.yahoo.net/common/phpserial.html). PHP developers will now be able to consume these web services even more easily than before. Yahoo!'s Search, Maps, and Travel REST web services now return serialized PHP by simply adding the "output=php" parameter to any web services request.
The example of this feature has been given in the form of a search for PHP-related podcasts: link here. The resulting output can then be used in a PHP application through the use of the unserialize function.