I found several examples of their socially responsible practices in this article by an apparent B & J's enthusiast that include not using milk from cows that have been treated with recombinant bovine growth hormone which increases chances of infection (and therefore, pain) for the cows. They actually pay the farmers who raise the cows that they get their milk from NOT to use this hormone.
Another interesting example mentioned in this article is their ice cream flavor, American Pie. This ice cream flavor not only taste like an American classic, but is also part of a political media campaign of the company's. Here's an article from Junk Food blog that goes more in depth on the topic. Basically, the ice cream container features a pie chart that illustrates government spending. The purpose is to make people aware of the government's spending on things like nuclear weapons and the war. This is socially responsible, however, it may not be the best PR in general. As you can see from the comments on this post, some people feel that Ben & Jerry's is alienating half of Americans (conservatives). That said, I think it succeeded in informing people about the issue.
Another issue people have been criticizing Ben & Jerry's for is its recent acquisition by Unilever. As B & J's has always been pretty outspoken against corporations, this acquisition came as kind of a shock. Many consumers wondered if the company would still be able to continue all of its socially responsible actions. This blog post from Ideoblog seems to think Ben & Jerry's is still doing a good job. They are teaching their employees about CSR too.
In general, I believe Ben & Jerry's is doing a good job. I also think whoever does their PR is doing a good job too because the word is definitely out there about their socially responsible practices and stances.
Seriously, no company is perfect. As wonderful as it would be for every company to be socially responsible in every aspect, that's a perfect world and that does not exist. I believe that Ben & Jerry's puts in the effort in many aspects of its company and that is more than many other companies are doing.
Here is a quote I found while doing my search on more information for Ben & Jerry's. While it does not have to do with the company specifically, I think it illustrates the purpose (and importance) of CSR quite nicely:
"Money should never be separated from values. Detached from values it may indeed be the root of all evil. Linked effectively to social purpose it can be the root of opportunity."
--- Rosabeth Moss Kanter, Professor, Harvard Business School