Well yes we do have "easter eggs. For those that aren't familiar with easter eggs in this context, they are hidden things to discover in a game (and sometimes in other types of software).
In FSX we have several. Some of them are hidden in missions, and others are hidden in free flight. All told I think we have 175 different rewards you can earn scattered throughout the world. I hope to have a rewards chart for the fsinsider site so you can have a better idea of what is really there.