I believe I saw this feature somewhere, but I can't remember where.
The point is this:
You are trying to read a topic (like TBC launch for example) but it is very hard to find relevant posts when there are over 30 pages of them. It would be nice when you read a topic on the forum, to have the option to filter posts and show Staff/Moderators only.
I'm not an expert on this, but I believe you can automatically tag those posts somehow in order to easily filter after.
I believe the mod team had discussed this internally in the past, but it didn't go anywhere for some reason.
However, if you're interested in having this, you can bookmark a staff profile (for example: http://forum.warmane.com/member.php?username=Mercy ), and when you want to check their posts, you can go to the profile and and click on "Find latest posts" on the left side.
That doesn't really help. You don't want to track a staff, you want to track a topic and stuff written by staff (any) on that topic only.
Anyway, I found out where this was and it was Blizzard forums.
However, they don't filter posts, they just change order, so visitors can choose to see Staff posts first on a topic.
If you think about it, it should't be that hard to implement, but I am not an expert. First, you have sql database with forum users, where some of them are staff members, so you should be able to identify those easily. Second, your posts default sorting criteria is the date on which they were posted.
In the end, all you need is a button to change sorting criteria based on what kind of users posted.