Not to say the others didn’t, but this is information you can extract with your eyeballs and not some sort of Da Vinci Code AR game shenanigans.
The number sequence “24.06.1459” suggests a date, the anniversary of which is coming up next month – well after E3. A quick search reveals nothing of immediate historical note on that day. Assassin’s Creed II and Brotherhood took place in the 1400’s.
The building seen in the background is the Hagia Sophia, in Istanbul. Again, a cursory glance turns up no particular significance for that date related to the famous landmark.
Ubisoft is expected to launch a new Assassin’s Creed title by the end of the year, strongly suspected to be called “Revelations“.