Searching for a while, I found hidden variable on login forms called RedirectURI is used to send someone somewhere after login. There isn't such a variable that you can append to a logout, but apparently you can add an ini file variable

such as
LogoutRedirect=/user/login

(http://ez.no/doc/ez_publish/technical_manual/3_9/reference/configuration...)

You could then have it go to a page of your choosing, but by that time your session will have been unset, so its not terribly useful besides sending them to the home page.