An excellent example from Charis.  A couple commented about a hotel on their blog, and got this response.  Obviously the hotel is monitoring their mentions in Technorati/ Google Blogsearch, and following up.

They were a bit disappointed when they found out on arrival that the restaurant was closed over the Christmas period. They mentioned this on the blog as part of their commentary of the places they visited whilst on holidays.

Just last week the head office of the hotel chain posted a comment on their blog to apologise about the restaurant being closed and to offer them a free bottle of wine at the hotel’s local eatery.

Source: The Better Banking Blog: Leveraging the blogosphere