I'd prefer this didn't happen. An anonymous visitor may just be a regular accessing the site from a different machine, or one who's just purged his cookies. I don't want to suddenly find myself looking at a completely different layout just because I happen to be logged out, or to have no idea what a non-member is talking about when they describe a front page I will hardly ever see. At present the only difference in appearance between logged in and not is a few details such as my name at the top right and the voting buttons. That's how I'd prefer it remain.
What if the front page looked a little more like this?
(Please assume that I'm trying to help. If you're polite and constructive (even if you hate this design) Omega will send you bundles of love in the post. If you're rude, I'll personally fund ninja assassins to hunt you down.)