So, I ran into a problem that is clearly covered in the SFDC Pages documentation. Hopefully I have this titled and tagged in enough ways, so that other people who run into this issue, don't spend as much time as I did, Googling for an answer.
Anyway, if you are trying to access a remote action from a Standard Layout or some other iFrame in Salesforce, make sure your class and method are both global!!
The answer can be found HERE, about a third of the way down.
