I hear lots of people talk about how their idea is some competitive advantage. Ideas are cheap. Ideas can be stolen. It's how you execute that counts, and that's what Jason's post drives home. Nicely done.
Certainly, business ideas on their own usually have little value without execution. But it really depends. If your differentiator is the idea, you are at greater risk of direct competition, and so spreading the idea around without first gaining a foothold is risky, especially if you discuss it with people who are entrepreneurial minded. Sometimes a startup needs breathing room to find a true differentiator beyond the idea. I bet there is a long, long list of people being "wronged" after discussing their plans with others. Feedback is certainly hugely valuable, but people need to be judicious with what, and to whom, they reveal.
The reason a lot of people say "ideas are cheap" isn't just because there is no problem in spreading them around. I don't know about other people, but I've never had an idea that, once I started to execute on it, didn't change a lot. Since (as far as I can tell) this is almost always the case, spreading the initial idea truly doesn't cost me anything.
Of course, there are fields this isn't true, but this generalization gets thrown around a lot in these circles because, for most people reading these blogs, it's true.