Multi-Posting application for sending a post to 100s of wordpress sites simultaneosy

Need a multi-posting desktop application with the ability to send one post to many URLs. We want the URLs and the Categories to be stored in an Excel or Text file we generate and stored for each company we are going to post for. Each company we are going to post for is setup on the destination URLs (post to URLs) with a user name and password. They are classified as Editors for the WordPress options they can access. Please note - we are posting for hundreds of different companies on hundreds of different WordPress blogs. We need to be able to post to 400 blogs in about 10 minutes - 2. Must have expert level experience in WordPress and PHP. Must be familiar with Plug-ins. Must have experience with Blogdesk or other similar applications.