I see it as a good thing, Just as we saw some major corporations stand up against prop 8. Standing up against bigotry is a good thing. Financially supporting an organization or politician that is working to harm people is bad. Just as it is a good thing when corporations take a stand to protect the environment and cause minimal harm to it.
For me, it is not a black and white issue in the way that you are mentioning. Ethics plays a big part in this. I don't like that corporations lobby Congress to create wars or harm people in order to maximize profit for major corporations. Anything for profit mentality is not ok. Unlimited influence is not ok. Corporations having more political influence than people is not ok. IMO, corporations, politicians, and laws should reflect that.
In regards to civil rights/gay rights, etc., a corporation taking no position on it actually helps the other side more than our side. It is a good thing when Home Depot speaks up in support of protecting the rights of people, and that they see it benefits them by supporting their employees as well.
Target, now they have really screwed up this issue and have lost tens of million (possibly much more) in sales because of it. Their CEO had the power to make the right decision and decided not to. I'm looking forward to the day to end of the current CEO's reign on Target.