It's essentially online bullying by people that want to silence you for having an opinion that is different than their own.
The ex-Mozilla CEO knows this well. An online bullying campaign was launched against him and he was forced to quit.
I see this especially in many of the open source and tech communities, which is why I no longer contribute.
I also don't post anything political on my Facebook account. A future employer may look at this and judge me before I'm even hired..and decide not to hire me. Just looking at my list of friends, most people don't seem to realize that this may be a problem.
The same power that gives special interest groups and individuals the ability to launch campaigns to get people fired gives companies the power to not hire you based on your lifestyle or personal beliefs.