This trend may have started changing in modern games, but I agree with foa that by and large games don't prominently feature minority characters in main roles. This is far from unique to games, but spans all forms of media. I remember reading an article about this standard for women and minorities in movies which measures the occurrences of, say, two women talking to each other for more than X amount of time on a subject that doesn't involve a man (or two black people on a subject that doesn't involve a white person). Megan or Miriel might know what it's called, but I'm too lazy to look it up. Anyway, the number is shockingly low, even in movies that have a prominent minority character. I doubt it's conscious racism in all cases, but it does display unconscious biases. Black characters in games/movies/whatever tend to be support/comic characters and women characters tend to be eye candy and possibly the love interest. That is their "roles" while the white guy saves the day.

However, I do think it is getting better, and I would not be surprised if it is getting better in video games faster than movies or mainstream TV. Gamers as a group are just as stupid as any other group, but there are younger and generally more socially liberal elements to the group than within the general population. Like foa, though, I have not been playing enough modern games lately to be able to comment specifically.