https://docs.google.com, when used with Google Gears turned on and allowed, will result in some kind of unreported error in the Gears backend, leaving its users with a blank page. I have a feeling that Gears cannot handle HTTPS connections, but I’m not sure. It could be just a Safari and/or OSX issue.
Others have reported endless authentication redirection, which makes sense if you study the URL that the HTTPS version always gets stuck on. (There’s a “redirect” parameter which points to https://docs.google.com/?pli=1, which, if followed manually, simply circles back around through the authentication again and sticks back at the same old blank page.) Hopefully Google takes notice and fixes this soon.