I have Omeka 1.4 installed on a Mac Lion system and can't get the Docs Viewer Plugin working. The viewer windows show up with the text: "Sorry, we are unable to retrieve the document for viewing or you don't have permission to view the document."
I've gone into the omeka files directory and set its permissions to read/write for all with no luck. Clicking on the filename displays it in the browser fine and the file will display on my personal Google docs page.
Since you say you're on a Mac system, I'm wondering if you have a web-accessible address, or if you're just able to access your site locally.
The Google Docs Viewer plugin only works when your site is globally accessible. Google's servers have to be able to fetch your file given a URL.
Thanks. That must be it. The college requires using VPN when accessing office machines from off campus. I expect that kind of network security would block Google in the Docs Viewer.