One part of large scale reputation management is to be able to automatically assess the public opinion. We believe that we need automated tools to analyse the myriads of statements found in social media. Luckily the natural language processing research community has been focused on this problem in recent years.
The area is usually referred to as sentiment analysis or opinion mining, and covers tasks such as detecting sentences that utter opinions, assessing whether an opinion is positive or negative, and summarization of opinions. Bo Pang has written a nice survey of the field: Opinion mining and sentiment analysis, which is freely downloadable.
The field has recently moved to new and important tasks such as sarcasm detection, which was presented in a paper last week at the International AAAI Conference on Weblogs and Social Media.