I'm tempted to downvote this, but maybe you know something I don't. The kernel module allows you to chmod +x a class, jar, or applet and execute it from the command line. Or run it from a script, or exec() it, or whatever. It essentially makes it a real executable alongside ELF. Is there some other way to accomplish this? What file association do you mean?
I believe he's talking about configuring your desktop environment such that it will launch .jar files with java (perhaps through a script intermediary), which is indeed not nearly as cool as what you're describing.