I was under the impression that CCleaner was supposed to clean out Java cache. On Windows 7, they are located at C:\users\username\appdata\locallow\sun\java\deployment\cache\6.0.
I have tried several times but the cache is never cleared. The same issue was brought up last year, but a fix has not been created. http://forum.piriform.com/index.php?showtopic=24572
Windows 7 Home Premium
Firefox 3.6.3
Java 1.6.0_20
CCleaner 2.32.1165