This story calls to mind the Chappelle Show skit where the policeman arrives at a black man's home in response to a 911 call over a breaking-and-entering. The policeman immediately assumes the black homeowner, not the white robber, is the culprit; when his assisstant points out the fact that there are pictures of the 'suspect' and his family all over the wall. The policeman thinks himself all the wiser when he says something to the effect of "oldest trick in the book. This guy came in here, hung up pictures of his family on the wall, then robbed 'em blind"
On this subject, however, a very conservative and Republican friend of mine - whose father happens to be a police officer - had something interesting to say: allegedly, in our county, there were statistically more crimes perpetrated by black males than any other demographic, by a considerable margin. Therefore, my friend argued that his father wasn't being racist in taking the occassional conclusional jump against a potential criminal based on race - he was just listening to the statistics.
I don't know how much I buy into that (since it seems like it's still a decision based on race, even if there are 'facts' to back it up...), but I think it's a tough issue. In this case, just based on my limited knowledge of the scenario, I'd agree with jdawg. There may - but also may not - have been racism involved in the officer's scuffle with Mr. Gates, but there almost certainly was racism in the neighbor's decision to call the police in the first place.
[ and really, had she not seen her neighbor even once? ]