Getting started with Oracle.

I'm a SCJP with some JSP, Servlet experience looking for full time Java related work. Every second job posting I see mentions Oracle to one degree or another. I would appreciate any suggestions that are out there about getting started. I would like to achieve a certification, but which one? I know a little about the JCert / Oracle cert but I'm not certain where to begin? Should I brace myself for the task of become an Oracle DBA, or is knowledge of JDeveloper sufficient?
Any books, courses or general information that someone can suggest will be grealy appreciated. I'm not afraid of alot of hard work, alot of reading and spending money where it's needed. Thanks.