How much to reveal to potential funders or business partners?

My team started talking about the yc winter 2010 app and it brought to light some questions about secrecy, honesty and the fear of being scooped. How often are ideas presented by one group given to a different group? How often does trying to secure funding actually create competition. The usual answer is that ideas are cheap; time, effort, resource and drive to implement ideas is rare. This seems to be true in general, but venture companies are in the unique position of have the financial and people resources to actually make use of ideas. Lots of people are likely moved by similar cultural forces and experiences, and thus moved to similar ideas. Most ideas are fairly general compared to the specific insights and mission that influence a company's success. Nonetheless, every year after the new yc teams are announced at least one person on the discussion list says, Hey, that's my idea (or insight)--why isn't my team good enough? Even when multiple teams are vying for the same niche, which I expect happens far more often than actual scooping, this is a bad feeling to have. Not a big deal business-wise, of course, other than the fact that one's business now has a better connected and more well known competitor getting better advice, etc (at least for the time being :-). I'm curious what people here think: Is trying for YC funding worth getting the ball rolling on a competitor, complete with the yc experience you're not getting? Should teams not reveal the whole idea or vision on their application, especially if it is the team not the idea that really counts? Is this an issue at all in the general world of acquiring funding? (context: i'm very much a backend, always honest (though at times wrong) developer. i believe most code should always be open source from the beginning, and i try to live up to my ideals about code and inclusive collaboration. i'm proud of my honesty and naive (or lazy, depending on how you look at it) willingness to trust. i also try to trust the person who is actually in charge of the business and funding side of things...still, i can't help but feel that secrecy is motivated by fear and not worth the loss it entails. is there some kind of balance that successful business-folk and entrepreneurs strike? holding back information from the good folks who read the yc apps seems wrong, even though i know it's a competition and we want to impress them more than other folks and not risk get scooped...if that is indeed a risk at all.)