Testing this on new wordpress install (v3.2.1) and using the latest plugin (v1.0.2) and unable to successfully login.
-tried with wordpress option 'anyone can register' enabled and disabled. -Went back to google's api page and copied all the information (name, id, secret, key)
-logged out of google and tried the button
-logged in via google and then tried the button
Is anyone successfully using this?