Originally posted by Spetnik
No, this one is more of an html template change, not a code change, and can be done quite easily.
Spetnik i meant change of the Logout button at the top, you will need a if statement to check.
e.g (Pseducode)

Code:
if user is logged in 
     show logout button //source of image e.g logout.gif
     set the link to logout page //e.g logout.php
else
    show the login button //source of the image e.g login.gif
    set the link to login page //e.g login.php
end if
I think you meant the placement of login/logout box that hobo pointed out, yes that you can change by modifying template.

Danial