I *hate* this behavior of Google websites. I log out of my profile often and any time I try to visit Groups or Docs (now Drive), even for publicly visible pages, it instead directs me to log in. I end up nuking all Google cookies instead and then the link works. Why do people who have no account with Google have an easier time accessing public Google pages than those who choose to log out do?
I know the (or rather, an) answer, but it's silly that it even has to be asked.