I am pretty sure MobileMe does
not support java.
If you're publishing that way, you need to serve the applet externally on your own web server where you've got it running and working just fine. In iWeb 08 add an HTML snippet via inspector and code it accordingly (example):
Code:
<APPLET CODEBASE="http://youripaddress:8080" ARCHIVE="your.jar" CODE="your.class" WIDTH=640 HEIGHT=480>
<PARAM NAME="x" VALUE="y">
</APPLET>
Meaning, use your own IP and port, your own archive including any optional path although best if you leave it at the document root, the class name, dimensions and any parameters your applet requires.
This advice is based on Google research, untested.
-jim