There was always the intention to allow mods to insert a random message in a topic as a staff member, with the yellow background.
We never quite got there, and very few people ask for it.
It would be nice though since on bbs.boingboing.net the mods do periodically post in topics to warn everyone that things are going off track – having that in the yellow “hey this is an official message not just me talking to everyone” staff color would definitely be useful since
- it would be more visible
- it would make it clear that “mod voice” was on