According to this new post on Lukas Smith's blog today, the PHP project has started a new effort aimed at helping out developers upgrading their PHP installations - a new README file with details on each upgraded version and its install.
In order to make the transistion for users upgrading to new minor (middle number increment) and major (leading number increment) version of PHP easier, the PHP project has recently begun adding a README with upgrade information with new releases. This guide steps through any issues that users are likely to be faced when upgrading their PHP installations.
Lukas also reminds developers that testing these releases is the only real way to find the bugs that are there and catch them before the final release for that version. Bug issues can be reported to the tracker and, if you'd like to see an example of this new README file for PHP 5.2, check out this example.