moebios Yes, it can be difficult to implement, but is very flexible once you have it figured out.
1. If you have music playing and you aren't switching it when you goto the menu, make sure you have it set (in the audio plugin) that music doesn't get saved, since it'll jump back when you switch back otherwise.
2. Since you'll be making changes in your menu, make sure you have an object that ignores saving and loading. Pass all of the changes you make to it's instance variables, then upon loading the previous layout move those values where they need to be.
3. Haven't messed with this one too much, but if you want to preserve part of the previous layout (As say, a background), create a sprite as your background, and have pausing take a snapshot of the layout (System action), then load the picture once you get to your menu.