I've 6+ years Oracle experience and many Oracle training certificate from Oracle(China) in 6 years(several versions of Oracle standard, advanced, develop2000, Oracle Financial). They didn't care the certificate in the interview and just ask me many questions about my experience and backgroud. When I showed them the training certificate, they even didn't like to see and just said: "Oh, maybe you don't need more trainings." I got the offer based on my background.
If you have time and money, you'd better to get the DBA or developer certificate (the training tuition is US dollar 5000 in Oracle China, the same price as in US and Canada. You could pass the test after such kind of training in 99% possibility. If you take the test without training, it's not easy to pass.). However, it's not very useful, but better than other certificate(Microsoft). I was thinking of such kind of certificate before, but it's too expensive and I thought my backgroud is OK, so I didn't take such training and test.