From one of WP engineers:
It’s not possible for you to publish a post and have it publicized under the blog owners credentials. It sounds like you are setup as an author on blog x. If you were setup as a contributor you could write the post but it would have to be published by the owner of the blog. They would then be authorized to publicize the post when they published it. Otherwise the only option would be to publicize the post manually through Twitter. You can find more information on User roles here:
http://en.support.wordpress.com/user-roles/
Okay just to clarify one thing, I am not talking about the owners WP
credentials but rather the owners Twitter credentials. In any case, I
thought there could be some kind of authorization like in any other twitter
application. Since the author needs to be authorized by the owner to be able
to be appointed and Twitter needs authorization from the owner to publish.
Unless I am missing a hole between these two closed paths.
In this case, I believe the Twitter credentials are tied to the individual’s WordPress.com credentials. When a post is published it looks at the information for the person publishing and pull the Twitter account info from there. To quote from the Publicize docs page:
“For multi-author blogs, each user that wants to connect to a Publicize service will need to do so separately as well.”
That page can be found here:
http://en.support.wordpress.com/publicize/
I think it would be a nice feature to attach a Twitter (Facebook, Yahoo, etc.) account to the blog so that all posts published there could be publicized through one account. I’ll pass that along to our developers and see what they think. There may be some complications with doing this that I haven’t thought of which may be why they didn’t implement the feature like that.