I had noticed this yesterday, according to various blogs I just have to rest the chmod permissions. In reality the only thing that changing permission does is prevent the pages being displayed at all. The sites seemed to previously only work when everything was set to chmod 555. Now I just have an refresh cycle when I submit any forms. Whats going on?
It's to do with the rewriting of your domain to the site on the filesystem, and PHP_SELF not being quite as expected as a result of this. I've explained this in the main thread however there's quite a lot in there so you may not have seen it. I beleive a fix is being worked on, in the meantime you can use $_SERVER['SCRIPT_URL'] in place of $PHP_SELF or $_SERVER['PHP_SELF'], which should resolve the issue.