Which is easier: iPhone or Android develoment?

That's the beauty of Mono...it allows you to run .NET code on either android or iOS devices...Mono is basically a .NET wrapper for the SDK's for each phone (there is a separate mono for each though).

Now each OS has its own caveats as far as it comes to user interaction and doing stuff with the UI...so that part of your code will be different in each app...but your core backend code can remain the same that does work.

Just make sure you separate your code into reusable classes...and make sure all the UI code is done separate from your code that does all the work...this way you can reuse the backend code in each project and only have to change the UI code.

So if you want to say, get recent facebook status, and show to the user, you want this to be two functions on two separate classes:

Data.cs class --> GetFacebookStatus() function

Presentation.cs class --> DisplayFacebookStatus() function. This would call GetFacebookStatus() and then display the data to the user, and you could wire this up to a button_click event handler.

The code in the Presentation.cs class will change for each OS since displaying to the user is different, but the Data.cs can be reused as it knows nothing about the UI and it's job is simply to get data.

What you don't want to do is have a single function that does both of these though as it will be harder to reuse your code in the other OS.

Hope this helps.

-Mark