The Zend Developer Zone has an article from Akash Mehta (reprinted from SitePoint) about creating a Yahoo! based mashup combining their search functionality and mapping.

In this article, I'll show you how to use the powerful collection of Yahoo! APIs to build a mashup with PHP 5. First we'll take a look at what APIs are, and the various offerings from Yahoo! that we can take advantage of. I'll demonstrate how to search the web using Yahoo!'s entire database with only three lines of code, then take you through the process of building an entire application to search for 'Pizza' in 'Palo Alto, CA' with only 25 lines of PHP code.

They show how to consume the RESTful data Yahoo provides via a custom class that makes calling the API simple. They also include the code (and HTML) you'll need to make the mapping for for the locations your search turned up.