I think I may already know my answer to this question considering that it's on a Drupal forum but let me describe the situation.
I'm a big fan of Drupal although I've never been able to master it. I understand how to set things. I understand the principles of the content types, permissions, menus, blocks, etc. I think I understand a lot however I do not have a handle on theming for Drupal. Despite my best efforts. I probably don't have a handle on a number of aspects of Drupal quite yet.
I currently work for a non-profit foundation that has many micro-sites and develops new ones often. I'm their new and only web developer and so what I propose will more or less be dependent on me. I'm seeking the best solution for them. They need to be able to communicate their messages across all their sites (or selected ones) as easily as possible. I have no experience dealing with multiple sites under Drupal so I'd like to know how easy it would be to do this.
For example they may want a newsfeed on all their micro-sites. Let's say there's micro-site A, B and C. They want to be able to write a post and decide that it'll appear on A and C. Then they'll write another post and decide it will only appear on B. And so forth. Is this possible with Drupal?