I guess the reason for the question is that you want transparent application failover(TAF) so that if one node fails you switch the transaction to the other node.
If I remeber correctly you will need to use the thick driver to use TAF and you will have to configure some server side stuff like the listener.ora. I think that with 10g the thin driver will also support this but it doesnt currently. Look up TAF in the RAC manuals
Be sure and use the JDBC libraries that match the db version (just ftp from one RAC node).
In some testing we had done a few months ago, we found the JDBC thin version we were using did not support redirection required by RAC to support load distribution. We could only connect to a specific node and not any available node.