Red light bulb
According to http://chowhound.chow.com/topics/965021, it means the thread is a "workshop". This new format is, IMO, exceptionally stupid. Since the threads on the confusingly-named Food "Quests" board are mostly from CHOW staffers, and have not generated much participation, it appears that many others share that opinion. I intend to avoid that board, and any others that are structured that way, but twice made the mistake of replying when a topic appeared in the gray footer at the bottom of CH pages, not realizing it was on FQ.