How to save a Scene during a game?

I know is impossible to save a level (or Not? :p) as a Scene while is in play mode, but I’m trying to do a simple LevelEditor that could obviously save the level you are making.

Anyone has some Documentation or ideas where I can start from?

(I’ve made so far how to write all GameObject and their position on a .txt file, but I don’t know how to load it and if there are other easy way).

i saved my scene data in an xml file (so all gameobjects, positions etc)

i used this to start with, it’s 1 script

http://wiki.unity3d.com/index.php?title=Save_and_Load_from_XML