The prereleases so far use the folder "user/local settings/application data" to store all data such as savegames, memorial files, screenshots, etc etc. However, this folder is not very user friendly as the folder can be quite a challenge to find. The folder is normally impossible to access under windows, you have to enable "show hidden folders" to see it. If you're on a shared machine, good chance you won't have permission at all to go there.

Now for savegames it's arguably a good idea to hide them away, but memorial files, screenshots and so on should be easy to access. Not to mention the .prc file that you may have to delete to be able to run the game after a crash. At the very least, it should be explained in the manual where to find the folder.