We're looking to upgrade all our hosting servers from PHP 5.2.16 to 5.3.13 on Monday July 2 2012.
Upgrading to PHP 5.3 allows us to offer a more modern PHP environment and allows us also to offer a more up to date selection of 1-click installs of popular applications and frameworks via Softaculous.
Existing PHP applications may break. PHP 5.3 introduces some backward incompatible changes. Any issues are likely to arise from your own code if it has not already been tested under PHP 5.3.
If you have any concerns, please get in touch.