Yes. Use the betas that are compatible with snow leopard, as shown on the front page of the website. The release versions are being updated soon, just trying to track down some VST weirdness in them at the moment. Haven’t had any real reports of anything wrong with the AU betas.
You must have…I KNOW that the AUs pass validation in Snow Leopard.
Make sure that you don’t have multiple copies of the plugin in more than one place, like in /Library/Audio/Plug-ins/components and /library/audio/plug-ins/components. Generally put your plugins in one place or the other, not both.