A number of things I have read recently have had the same saddening undertones to me lately.

Whether its queer folk expressing prejudice against heterosexuals, feminists who hate men, or people of color claiming that white activists who have no money coming into their neighborhood is a gentrification issue. http://www.anarchistnews.org/?q=node/8794

I hear about "gentrification" here in Oakland too.
Oakland has rent control, which means no tenant can be forced out or have their rent raised dramatically just because local property valuations have gone up.
Raising the average income in an area serves to increase the tax base, lower crime, and is not bad for a neighborhood.  If, thanks to rent control, no one is being displaced this means that, like in the clash between anarchists in Pittsburgh, what people are really fighting for is something activists spent years trying to dismantle: segregation.

Bigotry which comes from an oppressed group is still just as much bigotry as it is when it comes from wealthy straight white men. 
In all cases it is counter-productive.
Activists, please - stop alienating your allies just because they look different than you.

That is exactly what they want us to do.