One of the new baseline system requirements for SugarCRM 5.5 is that you have one of the 5.2.x versions of PHP installed on your server. This requirement was added to not only simplify our support matrix, but also be able to use some of the newer PHP features to make SugarCRM faster and more stable than before. But this requirement has put an extra burden on systems administrators to upgrade their systems to the newer PHP version. With many Linux distributions this could require manually compiling code, which no sys admin ever wants to have to do.
Fortunately, the folks at Oracle have provided a set of RPMs for free that will upgrade any RHEL (Red Hat Enterprise Linux) 4 or 5 system ( as well as any system based upon RHEL such as CentOS or Oracle Enterprise Linux ) to the latest PHP 5.2 version, ( 5.2.10 as of this writing ). They provide the full set of modules, including the oci8 extension for connecting to Oracle databases, in both 32 and 64 bit versions. They are unsupported by Oracle, but definitely make it much easier to upgrade to PHP 5.2 without manually compiling packages by hand. You can check out the project and download the RPMs at http://oss.oracle.com/projects/php/.