And below, excerpted from my post last April, are instructions for disabling Java in Safari, Firefox, or system-wide:
...consider turning off Java altogether in Safari. Go to Preferences in Safari, and click on the Security tab, then uncheck the Enable Java checkbox:
UPDATE: Several folks have asked how to disable Java in Firefox. Here are the instructions:
Open Firefox's preferences, go to the General tab, and then click on the "Manage Add-ons..." button in the lower right corner. That will open another Firefox window, showing a list of plug-ins, one of which is the 'Java Applet Plug-in'. Disable that plug-in, and you should be good to go...
To be even more secure (and aside from your browsers), you could disable Java system-wide. I don't recommend this, however, unless you're positive you don't use any Java-based programs (CrashPlan uses Java, for example). If you want to disable it, you will need to go to your Applications folder, find the Utilities folder within it, then a program called Java Preferences. Open that, and uncheck all the boxes under the General tab, as seen below:
Unfortunately, the online world just seems to get riskier as it gets more powerful. Keep reading your daily news to learn of the latest threats, and check back here for the details...