It dredges up racism, the KKK, white supremist scumbags, Nazis, Jew haters, and just plain hate. Some people claim that the confederate flag is a symbol of a wonderful southern heritage. Bullshit. If anyone choses to display this controversial symbol, s/he should not be surprised if others question the sanity of this act. Or, the outright stupidity. Racism is, after all, institutionalized insanity. And flag-waving hatred is dumb, at best.
Although people have the right to display whatever they want (hell, my avatar is one of very specific hatred), and I defend the First Amendment of the Constitution that protects free speech, I will never forget the message that hate symbols represent. And, I will also exercise my right of free speech and protest such symbology whereever and whenever I encounter it.
A website you might find rather entertaining on this subject is here http://www.cagle.com/news/flag/
Other good is the ADL site http://www.adl.org/hate_symbols/default_graphics.asp which includes all kinds of hate symbols, including the confederate flag.