Is CityVille the sequel to FrontierVille?

We've been bringing you lots of tips, tricks, and strategy guides for Zynga's newest Facebook game CityVille, but now it's time to take a look at something a bit different - that being a hint of where CityVille's origins might have truly come from, at least in terms of the in-game story.

After passing a mission that requires you to harvest crops, you'll come across a lost Love Letter in a Time Capsule, written on tattered brown paper, strangely resembling that of the letters found in another of Zynga's games - FrontierVille.

The text on the letter reads: "My Darling, I can't wait to join you on the frontier! Send for me when you can. With love, your spouse-to-be!"

For those that play FrontierVille, you'll recognize this letter as being similar to the one you receive from your spouse as you're beginning your quest to clear the homestead. Does this mean that the plot of land on which you're building your city in CityVille is actually where your old Frontier in FrontierVille once stood all of those virtual years ago?

It would make sense that Zynga would tie its other games into CityVille. For one, it will make users more comfortable to see familiar mechanics (like the bonus items that pop out of buildings upon collecting, just like in FrontierVille, or the farming of crops, like in FarmVille). For another, it sure will be a great way to keep players coming back for more, just to see how the game's story eventually unfolds.

Give us your thoughts on this lost Love Letter in the comments. Could the reference to FrontierVille be merely that - just a reference? Or is there something deeper behind the shout-out? Sound off in the comments.