Using the latest nightly build of JME and the current 2.1 jar and binary I get the following error when trying to run the tests:
Apr 23, 2008 2:32:41 PM class com.jmetest.physics.TestBasicJoints start()
SEVERE: Exception in game loop
java.lang.NoSuchMethodError: com.jme.system.lwjgl.LWJGLPropertiesDialog.<init>(Lcom/jme/system/PropertiesIO;Ljava/net/URL;)V
at com.jmetest.physics.SimplePhysicsTest.getAttributes(SimplePhysicsTest.java:63)
at com.jme.app.BaseGame.start(BaseGame.java:62)
at com.jmetest.physics.TestBasicJoints.main(TestBasicJoints.java:130)
The nightly is broken - thus your nightly build version is older than your jME Physics version. Use both CVS versions and it works.