As far as I know, OSCv3 will only support MySQL, though due to it being more OO than v2 it should be easier to write a patch for it to work with Oracle than it is with v2.
Some people in the OSC community have called for Oracle XE support so perhaps there may well be support for it with one of the future Beta releases, but there is nothing on their road-map at present to suggest they will.

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Lawrence