I used to have this fear too, of telling my friends what I was working on, especially my programmer friends, before I realized there are two types of scenarios:

I used to have this fear too, of telling my friends what I was working on, especially my programmer friends, before I realized there are two types of scenarios: 1. A person is that headstrong and passionate about your project and will steal it. They steal your idea and become successful. 2. The person says, "Oh that sounds awesome. Good luck with that." Then they move on with their life and I move on with mine. In most cases, #2 is more likely and logical, isn't it? How many people have you heard of doing #1? The only time #1 may occur is when you've already established the business and your business partner breaks away and enhances upon your idea. I don't mind telling people about my ideas or brainstorming because its most likely: I know what I want it to be like, they don't.. they just have a vague idea. They are probably not as passionate about you as your own projects. Thus: Get to it. Don't let that hold you back. In fact, embrace the times where people actually listen to your idea and give you feedback on it. It really does help.