For those that have made the switch to OSX Mavericks and are wondering how to get PHP and MySQL into a working state, Rob Allen has posted a quick guide to getting it all set up.
With OS X 10.9 Mavericks, Apple chose to ship PHP 5.4.17. This is how to set it up from a clean install of Mavericks. Note: If you don't want to use the built-in PHP or want to use version 5.5, then these are [other] alternatives: a binary package from Liip, Zend Server and a Homebrew install.
He provides all the commands you'll need to get things up and running including checking file/directory permissions, installing MySQL and using the command line to work with Apache (no more "Web Sharing"). He also includes the configuration changes to be made to the php.ini including how to enable Xdebug. There's lots of other good things included in the guide as well like setting up Composer, PHPUnit and how to compile a few handy extensions.