Oracle released a developers version of Oracle9i Database for OS X:
Oracle today announced the immediate availability of the Oracle9i Database Release 2 Developers Release on Mac OS X version 10.2 "Jaguar," Apple's UNIX-based operating system, as part of an early access program for the Oracle and Apple developer community. The software download is immediately available free-of-charge to all registered Oracle Technology Network members. With this release, Apple developers can build applications that leverage Oracle's leading database technology running on Xserve, Apple's powerful new rack-mount server.
Oracle originally announced support for Macintosh during the announcement of the Xserve.