Artanis,

  To actually start using MonoTouch or Mono For Android, costs you nothing as the trial version, which works with the respective simulator/emulators, is FREE. Only once you are ready to test on an actual device do you then need to pay $400. Xamarin have special offers through out the year too, so look out for those as well.

MonoGame will be adding ES 2.0 ( shaders, programmable pipeline etc) and 3D support in the new year, and we hope to support PlayStation Suite ( PS3, PS Vita and Sony Tablet and Other Sony certified devices ), when PS Suite ships, hopefully some time in 2012.

Check here for some MonoGame related videos.

I might be wrong, but doesn't monotouch for iOS/Android cost 400$ for each platform?

Seems a bit expensive for most starting developers, specially compared to similarly priced alternatives like unity3d that are more mature and can also be coded in C#.

I do see it as really interesting for MacOS and Linux thought.

Not trying to flame/bash here, just wondering.