If you have an Android phone and simply can't wait to try the Opera Mini 5 beta, you can install the Java version by using the Java/J2ME Runner (homepage) from Android Market. Be warned, though, that Opera Mini is currently very slow when installed this way. I'm not sure if this is because the Java environment is slow or because Opera Mini 5 needs more optimization. Perhaps a combination.
I have not tested it on anything but a HTC Magic. If anyone tests it on other Android devices, feel free to leave a comment about your experience.
Opera Mini 4 is really starting to show its age when you use it on touchscreen devices, so I'm hoping that an official release of Opera Mini 5 for Android is coming soon.