No. When you become a Ghost, you lose any physical presence, and living players will no longer be able to see you. They can't see your body on the map, and they can't see your messages in the chat. However, other Ghosts will still be able to see you. Interestingly, there used to be a super rare glitch where occasionally a living player would be able to see the Ghosts on the map and read their messages. This happened to me a couple of times, and it was surreal; I felt like the little boy in The Sixth Sense ("I see dead people").