The PHP Team has announced the release of the latest version of PHP, version 5.2.1. The changelog can be found at: http://www.php.net/ChangeLog-5.php#5.2.1

The key improvements of PHP 5.2.1 include:

• Several performance improvements in the engine, streams API and some Windows specific optimizations.
• PDO_MySQL now uses buffered queries by default and emulates prepared statements to bypass limitations of MySQL’s prepared statement API.
• Many improvements and enhancements to the filter and zip extensions.
• Memory limit is now always enabled, this includes Windows builds, with a default limit of 128 megabytes.
• Added several performance optimizations using faster Win32 APIs (this change means that PHP no longer supports Windows 98).
• FastCGI speed optimized build of PHP for Windows made available for downloading.
• Over 180 bug fixes.

Link: PHP 5.2.1 Release Announcement