Well, I have never faced a problem of posting while logged out, however I can see this being a problem because perlmonks has so many domain variants (I mean you can access PM via perlmonks.org, perlmonks.com, www.perlmonks.com, www.perlmonks.org and so on... and each of these variants require a separate login)

I anyone does implement the different-theme-while-you-are-logged-in thingie I really do hope there should be a setting in "User settings" where you can disable this option (or choose the same theme while logged in as default theme for anonymous monks) because I tend to like this default PM theme.

Just my thoughts...