If the rumours are true, there should be plugin 2 support under OSX… Well I upgraded to OSX SL yesterday, nice to have Java 6 at last! but has anyone found the plugin 2 support???
I think this is part of Safari not handling plugin2. did you try with FFox ?
BTW what version of Java are you running on snow leopard , 32 or 64 ?
$ java -version java version "1.6.0_15" Java(TM) SE Runtime Environment (build 1.6.0_15-b03-219) Java HotSpot(TM) 64-Bit Server VM (build 14.1-b02-90, mixed mode)
But you can easily change to 32 bit in the Java Prefferences application. The above is default under SL, the below is switching to 32bit
$ java -version java version "1.6.0_15" Java(TM) SE Runtime Environment (build 1.6.0_15-b03-219) Java HotSpot(TM) Client VM (build 14.1-b02-90, mixed mode)
Safari doesn’t even seem to handle webstart after the update 
but I had that once before after an update, and I just had to manually install the Java updates from apple… handy.
So my testing is mostly with Firefox, which handles the webstart, but doesn’t seem to handle the pluggin2 stuff. I just get the CompatibilityApplet as coppied from http://java.sun.com/javase/6/webnotes/6u10/plugin2/jnlp/index.html. So basically it seems to ignore the <param name="jnlp_href" value="/game/game.jnlp">
If I try to access that jnlp directly with the full URL, the app starts and I get my JOGL canvas displaying, but all the swing components are missing, argghhh! plus there is alot of white being drawn/redrawn.
So is this just me, or does someone have a this all working under OSX SL?