I wrote a blog post about this a few weeks ago: http://blog.opportunitycloud.com/2009/12/21/stealth-disease-...

Summary: "The cure for the First Mover Paranoia is to not view competitors as impassable roadblocks but as a verification that the idea actually works and has a market. That is in fact great news! Now the challenge becomes to find holes in the existing market (geographic, pricing, quality etc.) or to improve on what the competitor is doing."