Along with the annoucement about EE 2.4, EllisLab also mentioned that in the upcoming 2.6.0 release the MySQL and PHP version requirements will increase.
Lastly, I would like to note that our PHP and MySQL version requirements will change with the 2.6.0 ExpressionEngine release, giving you at least 3 months to prepare. Our PHP version requirement will be 5.2.4 and our MySQL requirement will be 5.0.3. Making the call now allows our developers to plan new features with optimized code while still giving our users plenty of time to make sure their hosting environment is compatible with ExpressionEngine’s future needs.
If you’re running on an older server config or your host is behind in updating PHP and MySQL, you have 3 months to get things in order. EllisLab is usually very conservative with their PHP and MySQL requirements1, so hopefully this won’t affect too many people.
The latest version of PHP at time of writing is 5.3.9 and the latest MySQL is 5.5. ↩