I've merged connection pooling (DRCP) and Fast Application Notification (FAN) suport to PHP 5.3's OCI8 extension. The PHP 5.3 OCI8 code is Beta - in fact, PHP 5.3 itself is still really "Development". (It would be handy to have problems reported before PHP 5.3 goes Production).
The OCI8 code is an update to that previously made available in OCI8 1.3.0 Beta on PECL. The README details the changes and an important Oracle 11g patch. I haven't built a new OCI8 PECL release; that'll have to wait for a week or so.
In the meantime, if you want to install the new extension on PHP 5.1 or 5.2, you can extract the oci8 directory from a PHP 5.3 snapshot.
Copy the new oci8 directory to your 5.x directory tree, making sure to backup and remove the existing 5.x ext/oci8 directory. Simply renaming it confuses the PHP build scripts. Rebuild the 'configure' script and do your normal configure and install steps. Something like:
tar -xjf php5.3-200801310130.tar.bz2
cd php-5.2.5
tar -cvf oci8_old.tar ./ext/oci8
rm -rf ext/oci8
cp $HOME/php5.3-200801310130.tar.bz2/oci8 ./ext
make clean
rm -rf config.cache autom4te.cache
./buildconf --force
./configure [...]
make install
Or, if you previously built OCI8 as a shared library, simply use phpize to build a replacement oci8.so.