We have implemented a major new feature in the blogs; the Private Blog
With this functionality, you are now able to create lists/groups of people and then when creating a new blog post, you can restrict the view to one or more of these particular lists.
Click on Blogs >> Blog Settings >> Private Blog and make your lists.
We have tested this software extensively but if you uncover anything, please let us know. Test this function among yourselves and enjoy the eureka moments!