it's certainly possible, but it's limited only by people's general inability to make games as art -- generally, they don't know how and there's little precedent.
However, I would say that SimCity and SimEarth were both political, as they hard-wired their sociological and scientific beliefs into the game rules. These included beliefs about economic growth, sustainability, climate change, etc, which have political implications. Also, Civilization has the same sort of assumptions coded as rules:
http://econ161.berkeley.edu/movable_type/archives/000806.html
Of course, this isn't the only kind of political game you could have. You could write a very story-heavy game where the story was politically charged in the same way a movie is.
There's also game design as performance art, where you make a game about Columbine shootings, or the WTC plane crashes, and the game itself isn't as important as the reaction from people who don't actually play it.