I don’t remember where I first heard the quote, but it’s one of my favorites:
Don’t worry about keeping your great idea a secret, if it’s good enough you will have to beat people over the head with it.
Or something to that effect. But it’s so true, and evident in so many instances. The Internet is a fantastic vehicle for showing ideas to the world before you even think about putting it into practice, and seeing what the reaction is.
Brad Burnham wrote a fascinating post titled "The Weird Economics of Information" about the correlation between "openness" and success. One of my favorite posts ever. His basic premise is:
I noticed that, at least anecdotally, there was a correlation between how
open entrepreneurs were with us and their ultimate success. Simply put
the entrepreneurs who are aggressively open in describing their plans
seem to do better than the ones who are cagey.
Hey, I’ve noticed that too! 
He goes on to guess that the reason for this is the desire to make your idea the best it can be:
Every time you describe your plans, you are providing a blueprint for a
competitor. So, why do they do it? My hypothesis is they do it because
their experience has taught them that, on average, every time they
describe their ideas, they learn more than they reveal, no matter how
much they reveal. And, as a result, they are able to concentrate
insight in a way that creates a defensible advantage for them.
What a fantastic insight. I have definitely seen this proven true myself.
This especially holds true if you’re open not just in your conversations, but with the entire Internet as well. If you’re open with the Internet it will help you to vet your ideas against a very intelligent audience, and they have a tendency to help you see any holes in your idea, recommend improvements, or to point you to somewhere else if it already exists. If I had kept my "great" ideas to myself I would never have really understood what the Semantic (aka Linked Data) Web is about–truly a revolutionary idea, which people are currently being beaten over the head with. The Internet is really very good at de-duping ideas. Simply put, if you do not share, you will not grow.
I remember a conversation I was having with Trent one time where I said something along the lines of "I can’t believe I’m telling you this, it’s a million dollar idea", and he did a good job of smacking me back to reality. Appreciate that Trent 
The price of playing in our current paradigm is exactly zero, no more and no less.
