As Chris Jones has mentioned in a new post to his blog, the latest release of the Oracle OCI8 drivers for PHP has been released on PECL (version 1.4.4).

PECL OCI8 1.4.4 has just been released. It fixes a potential memory corruption using oci_set_* functions seen on 64 bit machines. This release can be used to update OCI8 on earlier PHP versions.

He talks about an error he's come across many times - "Warning: oci_connect() [function.oci-connect]: OCIEnvNlsCreate() failed" - and how it can be fixed with an environment setting. He updated the error message in this new version to be a bit more descriptive and help lead others to the problem more quickly.