On Evil Genius Chronicles, there is a post about the “top 10 geek business myths“, and how true the reality of Myth #3 actually is and how it applies to various things.
Myth #3: Someone will steal your idea if you don’t protect it.
Reality: No one gives a damn about your idea until you actually succeed and by then it’s too late. Even on the off chance that you do manage to stumble across someone who is as excited about your idea as you are, if they have any brains they will join you rather than try to beat you. (And if they don’t have any brains then it doesn’t matter what they do.)
This goes for blogging as well. Darren Rowse knows this one well, as when he started making serious money in blogging about digital cameras, everyone and their brother went to make digital camera blogs. Before that, there were not many people pushing very hard in that space.
So again, people will only care about your idea once its great, and not before. So get your ideas out there. It is in the execution of the idea, not just the idea itself.