minimap signaling

dota players would know in warcraft 3 u could alt+click on a spot and that would show up as an exclamation mark with ripples on the minimap to alert your teammates of something happening in that area.  I havent played the beta, but i was wondering if this could be implemented if it hasnt been already.  also, for griefers who just like to spam it, there should be an option where one could disable signals from that person in the same manner if u were to mute someone.