It has been pointed out that the HTML 5 specification obsoletes the applet tag. The applet tag has been deprecated for some time. See http://forums.java.net/jive/thread.jspa?threadID=47204&tstart=0 .
Currently we do not set the appropriate registry keys during installation to support the use of the application/x-java-applet MIME type in IE. Additionally, there is code in the IE version of the Java Plug-In which assumes too strongly that CLSIDs are being used.
Appropriate changes must be made to enable the object tag with the application/x-java-applet MIME type to work in both IE and Firefox.