LinkedIn / Twitter / Facebook as OAuth and OpenId use

Question

Firstly I understand OpenId is for authentication and OAuth is for authorisation and unlike other questions on the site I am not asking which should be used for which bu

Answer 1

I don't want to ask a user to login with their account via openId then have to authorise the same account again via oauth to allow my site to publish to their service feed and have to do this for each of the 3 services.

I'm afraid you'll have to connect the user's account to each of the 3 services individually. What platform are you using to build your app? If it's Ruby, then a gem like OmniAuth looks promising.