This could really do wonders in Destiny if implemented in the correct way. I actually think we will see things in the game like this. For all we know they have already put out ARGs into the world without us knowing. I am still think about why they wrote Fallen as "Fa [u]ll[/u] e[u]n[/u]" on their poster. I think anything in game would work similarly to this but with some differences such as having to find the transmission as well. When the Cortana letters were released they weren't popular right away. It took a bit of time to get traction but eventually they took off. However, we already know about Destiny unlike how Halo was unknown to us when the letters came out. I think there are some things that have been secretly let out but most will be found during the release of the game and will hint at future releases and DLC.