I spoke with a friend who is an attorney about my intentions to develop and
market a software application.

He recommended that to protect myself I should write a Statement Of Intent To Develop
Software and have some withnesses sign it. Problem is, he is unsure what it should say.

Does anyone have anything like this? An example would be nice.

What kind of law does your friend practice? If he's "unsure what it should say", ask him if he can refer you to a lawyer or law firm that DOES know what it should say.

Don't get me wrong, there's great information on the web about standard text in documents like you're describing - but still, if you're serious about this kind of endeavor, find an attorney who specializes in this.