If I download and install the latest Mustang snapshot on Microsoft Windows (Windows 2000), it becomes the "default JVM", meaning that at least (a) it becomes the version I get if I do "java -version" in a command-line window, and (b) it gets used by JavaWS by an app that specifies version "1.4+" or the like. This seems a bit contradictory with the message that these are unstable, intermediate, at-your-own-risk builds.

Apparently it is possible to switch the default JVM back to a stable installation, but this is not prominently documented. Either unstable builds should not replace the default JVM, or the download pages should prominently document how to switch the default while keeping both the stable and unstable installations.