The 7u6 EA runtime doesn't have an icon. This may sound like a small thing, but even though you can't see it in the Finder, Sparkle will use the icon when doing the self-update. This lets the user know that it is the Java runtime requesting the user to update.

Jeff Hoffman has provided me with an icon in Mac 'icns' format, which is what the Finder requires. I just need to modify the Info.plist and a build script to copy it into the right place.