Not as good as you think
Although I haven't read the original HBR article yet, this piece in Computerworld offers an interesting interview with Dan Lovallo about why project managers are overly optimistic about the prospects of their IT projects. The research behind this was done with Daniel Kahneman, who won the Nobel prize in behavioral finance and it seems that the same basic reasons people are overly optimistic about their investment prowess makes them overly optimistic about project prospects as well. Basically, people overestimate their chances of success because everyone thinks they are above average and can't distance themselves enough from the problems at hand. What to do about it? Make sure you back off a little bit and get a reality check from an outside or disinterested source.
I saw Dr. Kahneman speak at UVa this spring and his perspective on decision making is very interesting and resonates with what I have observed (and done). I actually did change my investment habits based on his finding and now I'm even more convinced that the best thing to do is buy broad indexes. What is the analogy of buying broad indexes in project management?