According to an article in the current issue of the Journal of Marketing, the answer is yes.

To quote the abstract:

Do investments in customer satisfaction lead to excess returns? If so, are these returns associated with higher stock market risk? The empirical evidence the authors present in this article suggests that the answer to the first question is yes. Remarkably, however, the answer to the second question is no, suggesting that satisfied customers are economic assets with high returns and low risk.

While customer service isn't the only factor that goes into customer satisfaction, for many industries it's a crucial one. If the data in the article is correct, it should serve as a strong argument in the boardroom for prioritizing investments in technologies that lead directly to happy customers.