Latest build available here.
Building the .jar with Ant does not include OSGi.properties file properly. See latest build for correction.
Someone has reported an exception when core code loads 'net.jxta.impl.config'. At first, the culprit seemed to be the usage of ResourceBundle.getBundle() to load properties, but further analysis showed it was not the case. This is related to an Equinox bundling issue. The implementation of a solution is left to the next release.
Some people have reported the above exception under Mac OS and Linux when using the jxse-2.6.jar beta 2 release. However, this issue is not reported under Vista. A thread has been opened on the Java forum to discuss this.
See the latest build containing a patch for this issue. Let us know here if the issue persists in your environment.