Hello there, it has been only ten months since you asked. :)
If you *really* want to do this, you can by hacking /kernel/user/logout.php
When login out, you call /user/logout. Add a parameter representing the URL of your current page (that which you want to be redirected to).
Modify /kernel/user/logout.php so that it gets this parameter in $redirectURL (with some testing before, of course), and the last line of the code will do the trick
I think this feature is useful and worth submitting an enhancement request to http://issues.ez.no
While you could hack/patch the kernel 'user' module's 'logout' view php code.
I think it would be cleaner to create an extension, which contained a simple module view based on the stock logout view's php code modified to provide your enhancement.
The end result is the same except you would be simpler to upgrade your eZ publish without conflicts.
You might even use mod_rewrite to maintain the same logout url name to hide the fact that this uses a separate module extension to perform the custom logout. Example: '/user/logout' to '/customuser/customlogout'.
This extension would be worth contributing as well on http://projects.ez.no