From the Dev:
Boss Notes provides shareable notes and other information for your guild, party and raid community. The add-on lets you take notes from your boss encounter learnings and share this information with other players. You can also use Boss Notes as a general, structured in-game notepad. In addition, Boss Notes records trash and boss abilities as well as boss emotes and provides a collection of short encounter tactics. With the powerful Rules module, you can extend your existing boss mod with additional encounter rules for custom notifications, timers, raid target icons and yells.
A guy in a cataclysm PuG was using this the other day. He’d post notes on the upcoming boss fight into the party chat. Very cool. There was even a “scroll up” note at the end of long notes. You can grab it here, at Curse: Boss Notes Addon