Simplest way to use openid as authentication for static content
Depending on the volume of content, why not put it up on the Google App Engine?
There are restrictions on the amount of stuff you can put up statically (you can serve from DB though), and the number of changes per day.
If your content is small enough and doesn't change too frequently (100 times a day I believe is the max) this might address your authentication problems and simplify your life a fair bit!
For lighttpd, there is https://lighttpd-external-auth.chmd.fr.
I believe it could be ported for the nginx lua scripting interface without major difficulties.