JDK build
Tiger 1.5 b13

Since SHA256withRSA, SHA384withRSA, SHA512witRSA are new sig. algo. introduced for tiger

Testing Scenario
1. using keytool to generate a JCE Keystore with SHA384withRSA as signature algo.
2. write a test to retrieve the x509 cert from that JCE KeyStore
3. try to retrieve the sig. algo. name from that x509 cert
4. expecting SHA384withRSA, but I got 1.2.840.113549.1.1.12 which is the OID of that sig. algo.

How to reproduce
1. generate JCE Keystore using keytool
$JAVA_HOME/bin/keytool -genkey -storetype JCEKS -keyalg RSA -keysize 768 -sigalg SHA384withRSA -dname cn=YunKe -keypass keypasswd -keystore KeyStoreFromKeyTool -storepass storepasswd
2. list the keystore by using
$JAVA_HOME/bin/keytool -list -keystore KeyStoreFromKeyTool -storepass storepasswd -storetype JCEKS
3. copy and compile the following test code
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import java.io.PrintStream;
import java.io.IOException;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.security.Key;
import java.security.cert.X509Certificate;
import java.security.KeyStore;
import java.security.Security;
import javax.crypto.*;

public class testSigAlgo {
  char [] passwdStore = new String("storepasswd").toCharArray();
  char [] passwdKey = new String("keypasswd").toCharArray();
    FileInputStream inStream = null;
    String keyStoreName="KeyStoreFromKeyTool";
    String alias="mykey";

  public void run(String args[], PrintStream log, PrintStream out) {
    try {
      KeyStore ks = KeyStore.getInstance("jceks");
      inStream = new FileInputStream(keyStoreName);

      // load a keystore which was generated from keytool
      ks.load(inStream, passwdStore);

      out.println("Provider of KeyStore is " + ks.getProvider().getName());
      out.println("Type of KeyStore is " + ks.getType());
   
      X509Certificate cer = (X509Certificate) ks.getCertificate(alias);

      out.println("The signature algo. OID is "+cer.getSigAlgOID());
      out.println("The signature algo. Name is "+cer.getSigAlgName());
    }
    catch (Exception ex) {
      out.println("ERROR: unexpected exception - ");
      ex.printStackTrace();
      out.println("STATUS:Failed.");
    }
  }

  public static void main(String args[]) {
    testSigAlgo jstest = new testSigAlgo();
    jstest.run(args, System.err, System.out);
  }
}

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4. $JAVA_HOME/bin/java testSigAlgo
5. you will see
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nm-dtf-004.SFBay.Sun.COM:/home/stuartk/tmp/JCE/KeyStore( 41 )%java testSigAlgo.^R
java testSigAlgo
Provider of KeyStore is SunJCE
Type of KeyStore is jceks
The signature algo. OID is 1.2.840.113549.1.1.12
The signature algo. Name is 1.2.840.113549.1.1.12
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As you can see, I got the same output no matter which one I used
(either getSigAlgOID() or getSigAlgName())

Note:
The same test work with SHA1withRSA, MD2withRSA, MD5withRSA, only failed
with those new algo. (SHA256withRSA, SHA384withRSA, SHA512witRSA)