In fact, Sun pulled the feature before the final 1.4.2 release and had to include a last-minute notice about this on its release notes, saying that its own help info is wrong, and that a button that should be somewhere is actually not there.
See here.

The Help button in the Java Plug-in control panel displays text that makes reference to a "Get Java Update" button that is not actually present. Java Update is not included in 1.4.2. This is a future technology that will allow users to obtain the latest update for the Java 2 Runtime Environment.

So I apologize to readers who downloaded Java 1.4.2 and thought the auto-updater was there. The 2400 squashed Java bugs was true, the auto-updater was in the 1.4.2 beta but wasn't finally included in the final version. Shame on me.
Now Sun is now trying to get the recently pulled "auto-updater" for Java on Windows ironed out, and is asking for help testing this on Windows.
As you can see here , it offers a beta version of the "auto-updater" and promise "a chance to get a Java t-shirt", which sounds very little for the effort of downloading and installing beta code and rebooting your system, then clicking on the Java icon in the Control Panel, and then clicking on the "Update" tab, and then watching the systray icon download a bogus java update, and then clicking on the install button once the update is done, and then reporting back by e-mail if the thing explodes in the middle of the process.
Which poses a question, how am I supposed to claim or even be counted in the t-shirt giveaway process, if there was no form to complete? ยต [Please email Fernando with your answer, not me. Ed.]