Well, with cheats I was also thinking Trainers, and they do "MODify" the game. But what you mean by modding community is probably creating some new content or alternating existing one.. [something you could also do with a trainer, although most trainers usually end up giving you some sort of advantage (or disadvantage) in the game, instead of creating new 'options and methods' ...]
One thing I have noticed is that you are allowed to upload cheated results from your GALCIV games to the galciv com pages, and thereby increasing your score. Is there some method available for a trainer creator to 'flag' his game as a cheated game, so as to make the upload-game-results-to-a-web-page-thereby-giving-the-player-a-"wrong-score" impossible, or any plans to implement such in Galciv2?