Jason O'Donnell, who does Social Business for the Rational Client Support organization, has written several awesome blog posts on doing social business right, and one of his posts talks to this very subject:
I don't attempt to measure my social business with hashtags, simply because I don't think they are ever static or consistently applied by the world at large.
What do you think? Do hashtags add value for you or are they just clutter? Inquiring minds want to know! :-)