I have an application which uses these two properties: user.country, java.runtime.name. Although it seems that these properties are not needed (http://java.sun.com/j2se/1.5.0/docs/api/java/lang/System.html#getProperties()), I think it would be nice to support common properties that Sun supports. Users who need user.language, are likely to also need user.country.
Closing as won't fix as the Java front-end has been removed from the trunk.
Re-assigning to GNU Classpath.