Nope. Safari's not logging me out. It doesn't appear to remove a cookie when you try to expire it by setting the expiration date in the past. I encountered a similar problem while going through the exercises in Philip Greenspun's Internet Application Workbook, in the Basics chapter.
After clicking logout on openacs.org I can still get to /pvt/home. I've reported the problem to Apple and hopefully the next release will have a fix.
