This is easily something that a spamblog would want to do, but the people I'm working for seem to have a legit reason. It's a chain of stores and they want to be able to give an intern an Editor account on the main blog and post for each of the stores. They could make him an admin so he could create the post on each blog, but thats too much permission for comfort.
Alternatively, I was thinking maybe there was a plugin to give the intern an account on the master blog and create posts in a "Store News" category, with some way for that content to be syndicated to all child blogs.
Seems like something like this has been done. I found the Category Mapping plugin to go the other way: http://wordpress.org/extend/plugins/category-mapping-plugin-for-wordpress-mu/
Any ideas or suggestions? Thanks in advance!