We use Oracle and PHP together with some success. It seems there are a lot of rough edges as compared to, for instance, Java + Oracle. I am familiar with the Underground PHP + Oracle guide and that there is information scattered around the net. While OCI8 seems to work in most cases, there is noticeably a lack of support for PDO. There is an Oracle PDO extension but it is buggy and Oracle itself suggests against using it in the Underground guide.
I guess what I'm saying is that MySQL and PostgreSQL support in PHP appears to be much more mature.
This is definitely a community wiki, as I am trying to get a feel for what other organizations using PHP + Oracle together are doing. Do you use the PDO_OCI extension even though it is not recommended, or do you use OCI8 exclusively? What PHP frameworks do you use? Is it frustrating to develop with these two technologies? Have you migrated from PHP to something else in an enterprise setting, and if so, what?
EDIT: How do I mark a post as community wiki? Seems not to be an option any longer.