There are plenty of tools that can help with an editorial process. Google docs allows comments and multiple user access. You can email Microsoft Word documents back and forth with changes tracked. Even Evernote has nice sharing features.
But the best tool is the WordPress plugin Edit Flow. Obviously you need to be using WordPress for your blog to use this tool. If you are not using WordPress, and you are serious about building a blog for your business, you need to switch. I see no way around it.
Edit Flow is a very professional plugin and very good at what it does. Be prepared to customize it to your needs.