Chris Dixon and Charlie O'Donnell both advocate the value of the "blog as resume" and recommend starting one to everyone who asked for their career advice. I'll join that chorus as well. We have hired all of our junior investment professionals largely on the basis of their blogs, not their resumes or linkedin profiles. You can learn so much more about a person by reading their blog.

So to all the people out there wondering about the role of social media in their career plans, I second David Karp's recommendation. Build and own your online brand and don't let others define it for you. 

Fred, as usual, says it better than I ever could.