Does sharing your goals/ambitions lead to increased chance of failure?

Accord to the Derek Sivers research above, people who share their goals and ambitions are less likely to achieve them. I disagree with this for a few reasons:
1. Say I share a goal with 10 friends around wanting to learn Mandarin. There is a possibility that one of the ten has either had the same goal or knows someone else who has. If they achieved the goal, they are able to share advice. If they failed, they can share learnings and potential pitfalls. The sharing of experience is beneficial.
2. If you share a goal with close friends and family, they are likely to ask you for an update on your progress when they see you. "How are the violin lessons going?" "Have you shed that fat ass yet?"...these could act as sources for motivation.
3. When we share our goals with people, it can often put pressure on us to achieve them. It is like making a pledge. A secret goal can disappear out of sight without notice, reaction, accountability. I guess this point depends on the individual and whether their motivation comes from intrinsic or extrinsic sources.

Where do you stand on this? Agree or Disagree? Answer as ever on a postcard (preferably with an amusing picture on the front...)