Gennady Feldman recently spent some time doing some upgrades on his Oracle servers and, in doing so had a chance to work with the latest release of their Instant Client and how it interacts with the OCI8 extension's API.
I was recently involved in upgrading our Application servers to the latest Oracle Instant Client 11.g (18.104.22.168) including installing the latest PHP OCI8 module (1.4.1). Currently Oracle provides binaries for Linux in RPM and ZIP(?) format. (Side note: It still puzzles me as to why Oracle uses ZIP files for Linux binaries as ZIP is common to Windows and is not always available or generally used on Linux.)
He had everything prepared for the move and thought things would go smoothly during the upgrade but was surprised by a few things - the RPMs that Oracle gives are broken, an issue on the pecl update for the oci8 extension and a problem that came up with dependencies and packages for the Instant Client.